Interesting Horn Corals

Horn Coral
Horn Coral Fossils (Grewingkia, canadensis) #1

The horn corals have long gone by the wayside, but in their heyday, they must have added an extraordinary beauty to the diorama of the Paleozoic seafloor. Some varieties dominated the underwater, prehistoric scene reaching multiple-meters in height. At night, the coral animal flung out its long tentacles in order to sweep up unsuspecting tiny organisms passing by in the ocean currents.

Horn Coral Fossil (Heliophyllum) #2

Horn corals (rugose corals) attached themselves to the seafloor with the narrowed ends of their exoskeletons. As the organism grew, the top-end widened where the tentacles were encased; hence the reference to the shape of a horn.

Horn corals were extremely abundant during the Paleozoic time slot and most were individual varieties with a few colony variety exceptions.

Prehistoric Horn Corals
Prehistoric Horn Corals Rendering Drawing

Two Horn Coral Species Classification

Scientific Name: #1 Grewingkia, canadensis             #2 Heliophyllum

Common Name: Horn Coral                                       Same

Kingdom: Animalia                                                     Same

Phylum: Cnardia (means to sting)                              Same

Class: Anthozoa (means flower animal)                   Same

Order: Rugosa (means wrinkled wall)                       Same  

Suborder: Stauriida                                                    Same

Family: Streptelasmatidae                                      Zaphrentidea

Genus:  Grewingkia                                                Heliophyllum

Species: canadensis                                                  Unknown

Horn Coral Internal Structure

As a general rule, rugose coral have stronger radial septa (septum) or vertical growth walls that radiate outward from the center (like bicycle spokes). Rugose corals differ from other corals due to this pattern by which they add septa throughout their growth spurts. Named for their wrinkly outer skin, they possessed less developed horizontal partitions, but stronger vertical ones.


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