1. Finger Corals

Branching Type Coral Fossil
Finger Coral Fossil/Skeleton

I inherited a collection of coral skeletons discovered by my late mother-in-law, Winkie, lying on Florida beaches during family vacations in the 70’s and 80’s before preservation laws forbid people from collecting them. She was not familiar with the world-wide-web, but would have been thrilled to share them with you. I’m sure she’s very pleased in spirit.

Finger Corals are the first from a list of eight of Winkie’s coral species presented in this category, plus a link to my feature article about her Star Corals:

  1. Finger Coral
  2. Maze Coral
  3. Rose Coral
  4. Low Relief Lettuce Coral
  5. Cactus Coral
  6. Pillar Coral
  7. Brain Coral
  8. Brain Coral
  9. 7 Star Corals

To begin, finger-like corals are a dominant species in the Caribbean, Florida and Bahamas ocean reefs and form some of the largest colonies extending as high as 8 meters (26 feet) tall. They are a very slow growing form and therefore some may be a thousand years old!

Because the fossil/skeleton sample in my possession has broken off branches (very typical) I was unable to identify the exact species, but am certain it belongs to the genus called, Porites. Three Western Atlantic Porites species have features that overlap so they can be difficult to pin exactly. Below are brief descriptions and photos of these three varieties.

Club Tip Finger Coral
Club Tip Finger Coral
  • Club Tip Finger Coral (Porites, porites) possess thick, stubby branches growing upright or spread wide apart. Often gray, occasionally bright blue  
Source: http://foro.fonditos.com/porites-furcata-80-t54240.html
Branching Finger Coral 
  • Branching Finger Coral (Porites, furcata) possess elongated, tightly compact branches with rounded tips. Usually grey
Thin Finger Coral Source: http://reefguide.org/thinfingercoral.html
Thin Finger Coral
  • Thin Finger Coral (Porites, divaricata) possess most slender branches, widely spaced apart, often divided at their tips. Colors vary from purple, yellowish brown, grey and brown.


  • Kingdom: Animalia
  • Phylum: Cnardia (stinging cells)
  • Class: Anthozoa (flower animl)
  • Order: Scleractinia (stony coral)
  • Family: Poritidae (massive reef builders)
  • Genus: Porites (finger-like)


2. Maze Coral or Is It Rose Coral

Maze Coral Source: http://en.wikipedia.org/wiki/Meandrina_meandrites
Maze Coral (Meandrina, meandrites) Living Sample

Judging from the title of this article, you may have gathered their can be some confusion when identifying coral fossils and you would be right. All corals are not single organisms, but rather are a colony of individuals we know as polyps (the jelly-like part). The polyps band together and slowly build a calcium carbonate skeleton. Herein lies the physical diversity of corals as each species builds a slightly different style of skeleton.

I was confused by several coral species that I now feel confident about their identities after some head scratching and investigating. Maze Coral and Rose Coral fossil skeletons look very similar at first glance; descriptions explained below which solved the puzzle.

Both species are commonly found in the Bahamas, Caribbean and Florida shores.

Rose Coral Fossil
Maze Coral Fossil (Meandrina, meandrites) Fossil Skeleton

While researching, I realized that maze corals are sometimes lumped together with brain corals, or are even called maze-brain corals.  The most distinguishing features from other brain corals is that the maze-brain coral have thicker convoluted ridges and well defined plates. Also, there is an indentation running along the crest of the walls where the adjoining plates “corallites” meet. Colonies form both flat heads and or hemispherical (half-sphere) plates which fit the description of the one in the photo above; colors tend to be brownish or greyish.

Habitat: A wide range of habitats across the Caribbean, Gulf of Mexico, Bermuda, the Bahamas and Florida occurring at any depth less than 80 meters (260 feet) in reef-environments.


  • Kingdom: Animalia
  • Phylum: Cnidaria (Animal with stinging cells)
  • Class: Anthozoa (Flower like animals)
  • Subclass: Hexacorallia (polygonal corals having parts in multiples of 6)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Meandrininidae (Meandering Colony Corals)
  • Genus: Meandrina (forms massive hemispherical heads or have large flat plates and can grow to one meter (3 feet) across)
  • Species: M. meandrites

3. Rose Coral

Rose Coral (Manicina, areolata) Fossil Skeleton
Rose Coral (Manicina, areolata) Fossil Skeleton
(Shows Cone Shape Underside)

Two Growth Forms of Rose Coral

Rose Coral, Manicina, areolata occurs in two distinct growth patterns making matters of identification even more confusing. The first form consists of semicircular heads with wide, winding valleys and ridges forming irregular furrows; and with irregular cone-shaped undersides. (Shown above in the fossil skeleton photos)

Manicina areolata Source: coral.aim.gov.au
Rose Coral (Manicina, areolata) Living Sample

The other and most common rose corals form elliptical or oval colonies with a long, continuous central valley with several short, side valleys, and lastly, a short stalk underside. (Seen in the living sample and fossil skeleton samples below)

Interesting Behavior

Rose corals are one of only a few corals that can be actively mobile. If a small colony of rose corals gets turned upside down, it proceeds to gorge its stomach with water in order to bloat, and then it jets the water out from one side at a time. This causes a back and forth rocking motion until the center of gravity shifts, allowing it to rapidly flip upright. The entire process takes a few hours until it finally flips over in an instant. 

Underside: Rose Coral (Manicina, areolata)l Fossil Skeleton
Rose Coral (Manicina, areolata) Fossil Skeleton

Habitat: Rose coral Manicina, aerolata is very abundant off the Floridian shores as well as the Bahamas and Caribbean. It prefers shallow, productive, near shore habitats characterized by abundant sediments such as seagrass meadows, or along the fringes of mangrove forests. Larger colonies are more likely to die by smothering in the sediments placing a limit on the size any given colony can grow.

Colors: Yellowish-brown, tan or dark brown, often with the valleys and walls being contrasting colors. Like most corals, the polyps are only extended at night and are often green.

Manicina aerolata Source: http://reefguide.org/carib/rosecoral.html
Rose Coral (Manicina, aerolata) Living Sample


  • Kingdom: Animalia
  • Phylum: Cnidaria (Animals with stinging cells)
  • Class: Anthozoa (Flower Animal)
  • Order: Scleractinia (Stony Skeleton)
  • Family: Faviidae (generally spherical shape and grooved surface which resembles a brain)
    Genus: Manicina
  • Species: M. areolata

Note: The genusManicina, includes over 10 species, but Manicina, areolata is the only species that survives today. The heyday for Manicina was during the Miocene and Pliocene epochs between (24 million to 1.6 million years ago). About one million years ago, approximately half the species of reef corals living in the Caribbean became extinct.

4. Low Relief Lettuce Coral

Low Relief Lettuce Coral Fossil (Agaricia, humilis)
Low Relief Lettuce Coral Fossil (Agaricia, humilis) Fossil Skeleton

Low relief lettuce coral is fairly common with a widespread distribution in the open seas of the Caribbean, Bahamas and Florida, often scattered among other corals within inner bays and sometimes within mangrove roots. It can thrive from shallow sea levels to the lower depth limits of the reef, approximately 60 meters (200 feet) deep. It shows a number of growth forms, such as appearing saucer-like on cliff sides or small half-moon shaped in shallow depths. In depths deeper than 10  meters (3 feet), the coral forms broad vertical scales with corallites on one side only.

Low Relief Lettuce Coral
Low Relief Lettuce Coral (Agaricia, humilis) Living Sample


  • Kingdom: Animalia
  • Phylum: Cnidardia (C is silent) Marine group with stinging cells
  • Class: Anthozoa – Flower Animal
  • Order: Scleratinia – Reef building stony corals
  • Family: Agariciidae – includes cactus corals, elephant skin corals, plate corals and lettuce corals. Members of the family include symbiotic algae called Zooxanthellae in their tissues which help provide their energy
  • Genus: Agaricia – lettuce corals
  • Species: humilis – low relief
Winkie, Joe, Johnny and Joey
Winkie, Joe, Johnny and Joey, 1950’s


As I mentioned in previous posts, my mother in law, Winifred (Winkie) loved collecting coral during Florida vacations in the 70’s and 80’s. My late husband, Joseph III, came from a hard working family in the 50’s living in Detroit. His dad, Joseph II, was a designer for Chrysler Corporation and designed an amphibious vehicle used in WWII.    

I feel honored to have samples from her coral collection and am excited to share them with you. She would have been thrilled by this.  

5. Cactus Coral Pavona

Fossil Skeleton Shows Closely Spaced Polyps of Cactus Coral (Pavona)

After much digging around I finally identified this amazing specimen as a cactus coral from the genus of Pavona. The small prickly pattern of polyp corallites was the best defining feature, as well as the folding plates that loosely resemble a cactus.

Cactus Coral Pavona
Cactus Coral (Pavona) Living Sample

The Pavona, Cactus Coral is a small-polyp, stony coral which has been called, Cactus, Potato Chip, or Lettuce Coral.  A single species may vary in form according to the currents, wave action, lighting conditions and depth of its location. They can also vary in color from shades of light and dark brown to green with cream or white margins. Some have a fluorescent glow that can be seen beneath the polyps, giving these corals an interesting look. They are known to make a popular addition to the home aquarium.

Cactus Coral Pavona Source: "Douglas Illistration":http://www.freewebs.com/douglasillustration/reeftank.htm
Cactus Coral (Pavona) Living Sample


Kingdom: Animalia
Phylum: Cnidardia (A group containing over 10,000 species of animals found exclusively in aquatic and mostly marine environments. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey by shooting off a threadlike, often toxic, tubule from inside the cnidocyst.)
Class: Anthozoa (Flower Animal)
Order: Scleratinia (Stony corals which are marine corals that generate a hard skeleton. They first appeared in the Middle Triassic and descended from the tabulate and rugose corals that barely survived the end of the Permian. Much of the framework of today’s coral reefs is formed by scleractinians. Stony coral numbers are expected to decline due to the effects of global warning and increased acidity due to pollution.)
Family: Agariciidae (Reef building stony corals including cactus corals, elephant skin corals, plate corals and lettuce corals.)
Genus: Pavona (Coral colonies of this type have vertical, irregular, two-sided fronds.)
Species: Possibly minuta or duerdeni

6. Pillar Coral

Pillar Coral Fossil (Dendrogyra, cylindricus)
Pillar Coral (Dendrogyra, cylindricus) Fossil Skeleton

Pillar Coral is one of the most spectacular stony corals found in the Western Atlantic Ocean and Caribbean Sea. It derives its name for obvious reasons from its sizeable finger-like branches. They can reach a height of nearly 3 meters (9 feet).

Coral colonies were once more common along the Florida reefs, but commercial collections and coral bleaching has greatly reduced the occurrence of Pillar Corals.

Pillar Coral (Dendrogyra, cylindricus)  Source: en.wikipedia.org
Pillar Coral (Dendrogyra, cylindricus) Living Sample

Pillar Corals extend their polyp tentacles during the daytime, unlike most other stony corals.  The  tentacles gently sway with the currents and if one of the polyps is touched by something foreign, it swiftly contracts causing a wave of shriveling polyps pass over the entire colony in a period of a few seconds.     

Check out this exceptional photo of Pillar Coral


Kingdom: Animalia

Phylum: Cnidardia (Large marine group characterized with stinging cells, tentacles and no skeletons or organs)

Class: Anthozoa (Flower Animal)

Order: Scleratinia (Stony Coral)

Suborder: Faviidae (General Spherical Shape)

Family: Meandrinidae (Meandering valleys between corallites)

Genus: Dendrogyra

Species: Cylindricus

What’s being done to bring back threats to coral reefs? Coral farming; see video to find out about this effort to restore the reef along Florida Keys.

I hope you enjoyed this display of Pillar Corals and learned some new things along the way. I feel privileged to have inherited this sample as part of a collection from my beautiful mother-in-law, Winkie.

1983 Ft. Lauderdale Florida Winky and Joe
1983 Ft. Lauderdale Florida
Winkie and Father-in-Law, Joe

7. Boulder Brain Coral

I have two species of coral from my collection that have earned the common name, Brain Corals, due to their convoluted surfaces, loosely resembling the physical brain and general spherical shapes. They are both slow growing, colony forms which may reach colossal sizes to a few meters in length and live for hundreds of years. The oldest know brain coral is 900 years old. Both species below grow in shallow parts of the Caribbean Sea, the Bahamas, Bermuda, Texas and Florida.

Boulder Brain Coral (Colpophyllia, natans) Fossil Skeleton

Boulder Brain Coral (Colpophyllia, natans) is a very large brain coral whose domed, hemispherical colonies may exceed one meter ( 3 feet) across, but smaller colonies may be flat topped discs depending on location. The polyp valleys on the surface may stretch the entire width, or be subdivided into shorter series. The valleys and walls may be two centimeters broad distinguishing it from my Symmetrical Brain Coral (shown below) which have narrower valleys and walls. Also, the walls of the Boulder Brain Coral commonly have a fine grooves running along the tops. There is a sharp break between the wall and the valley floor. The colors vary with ridges being various shades of brown, and the valleys either whitish, green, or tan.

Boulder Brain Coral (Colpophyllia, natans) Living Sample Source

8. Symmetrical Brain Coral

Symmetrical Brain Coral (Diploria, strigosa) Fossil Skeleton

Symmetrical Brain Coral (Diploria, strigosa) forms flat plates or massive hemispherical domes up to 2 meters, (6 feet) in diameters. Sometimes, they will show a very narrow groove along the tops of the walls, which have sloping or rounded sides. Valleys may run straight for considerable distances or be highly irregular in direction. They range in color from purplish brown to grey or green, often with the groove floors being a contrasting paler color. Diploria, strigosa is the most widespread of all the Diploria species, being more resistant to threats with the ability to thrive in muddy stretches of seabed where many other corals are not able to flourish.

Symmetrical Brain Coral (Diploria, strigosa) Source: http://reefguide.org/carib/pixhtml/symmetricalbrain2.html
Symmetrical Brain Coral (Diploria, strigosa) Living Sample

Brain Corals Habitat  Source: http://www.dcbiodata.net/explorer/results/detail/5260
Brain Coral Habitat

NOTE ABOUT SCLERACTINIA: The order, Scleractinia, in which all living corals belong today, means they develop a stony skeleton, which is a light, porous skeleton consisting of external sheathing forming a cup. Scleractinians were fairly rare in North America until the Cretaceous, about 100 million years ago, when they first built reefs in Texas and Mexico. It wasn’t until the Pleistocene Period, about 2.6 million years ago, that reefs flourished where they do today.

Brain Coral Open Polyps At Night
Brain Coral Open Polyps At Night

Night Time Activity : Coral polyps, the living breathing jelly-like part of the animal, are found in single file in the valleys of this brain coral’s convoluted ridges. They are normally contracted during daylight, but expand at night to catch micro-bits of food drifting by.


  • Kingdom  –  Animalia
  • Phylum  –    Cnidaria (means stinging cells)
  • Class  –     Anthozoa (means flower animal)
  • Order  –  Scleratinia (stony skeleton)
  • Family  –  Faviidae (spherical group with grooved surfaces)
  • Genus  –  Diploria /  Colpophyllia
  • Species – strigosa /  natans

Identification and interesting facts about 7 species of Star Corals

© 2022 Kathi Mirto