Tag Archives: paleozoic fossil

Crinoid Fossils or Lucky Stones or Indian Beads?

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Crinoid “Sea Lily” Fossil Pieces

Collectors with a keen eye love to find these tiny crinoid fossil stems and sections along the shores of Lake Michigan, if they are lucky enough, hence the common name given them “Lucky Stones”. The largest crinoid fossil in the photo above is just under the size of a dime so you can imagine the luck in finding one in the sand or among the beach gravel. These extinct species are also referred to as “Sea Lilies“ explained by their colorful flower-like appearance as living creatures. They were actually a type of invertebrate animal that possessed long branching arms and a midsection that sat atop of a single slender stem, sometimes reaching two meters above the seafloor. Feathery tentacles at the tips of their branching arms trapped tiny food particles floating by in the ocean currents.

Crinoid Sea Lily Fossil

Crinoids were sessile creatures, meaning they attached themselves directly to the seafloor or underwater rocks or even sunken wood. A spawning of their offspring from these bottom bound creatures may have resembled the spring releasing of thousands of dandelion seeds blowing by in a gust of wind.

Crinoid Broken Stem Fossils
Crinoid Broken Stem Fossils

Crinoid skeleton fossils are usually found broken up into individual “cheerio” shaped sections or partial stems. Each circular section was stacked one over the other forming the entire animal framework. The Native Americans used the fragmented fossilized sections for stringing necklaces. Consequently, yet another fitting common name for them is “Indian Beads”.

Embedded Crinoid Pieces found on Oval Beach, Lake Michigan

Crinoid’s amazing history dates back as early as the Ordovician Period around 500 million-years-ago, but their heyday happened during the Mississippian Period around 345 mya. Their fossil remains are found widespread in North America explained by the fact that much of the continent was covered under warm shallow seas. The sea lily crinoids were a dominant feature in the Paleozoic Era seas, but most varieties succumbed to the great Permian extinction around 252 mya. Today, a few species subsit in cold deep-water environments, but dwarf in length compared to the prehistoric varieties.

Crinoid Classification

Kingdom: Animalia

Phylum:   Echinoderm (means spiny skin, i.e. starfish, sea urchins, feather stars, crinoids)

Class:     Crinoid (means flower form)

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Crinoids “Sea Lilies” Rendering Drawing in the Ancient Seas

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Interesting Facts About Trilobites

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Calymene, celebra Trilobite Fossil

Most trilobites grew to only about 3 inches (7.6 cm) long, while a few reached almost 3 feet (1 meter) long. This Calymene, celebra fossil fits nicely into a man’s palm. In life, it was a scavenger finding food on the ocean floor where it could easily burrow underneath the sand to hide from predators. Many of their fossils are often found rolled up in a defensive position. They were able to bend because their chiton exoskeletons were fitted with overlapping sections. Think of roly-poly bugs, or pill bugs, as some call them; it’s the same idea.

Lifestyle of Trilobites

Trilobites developed several different life styles; some moved over the seabed as predators or scavengers, while others were filter feeders, yet some swam along the ocean strata feeding on plankton. Most were sluggish swimmers, while some later varieties were designed precisely for speed and swam in the mid-ocean, pelagic zones where more predators existed. 

Calymene, celebra Trilobite Fossil

This little Calymene trilobite crawled on the ocean floor over 400 million years ago during the Devonian time period. His species had smaller eyes than many other trilobite species and was probably a sluggish swimmer. A good number of their fossils are found in Michigan and other Midwest states where warm shallow oceans once dominated the continents.

Trilobites have the distinction of possessing a segmented body, multiple jointed limbs and an armored outer shell, placing them in the category of arthropods related to insects and crustaceans. Trilobite means three lobes in Greek, from tri and lobos, named for their three major lengthwise body sections.

All trilobites died out at the end of the Permian mass extinction event, 251 million-years-ago, which removed over 90% of all species on Earth.

Find out about a few giant sized trilobites here in another article I’ve written. (Scroll down to middle of page)

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Calymene Trilobite Rendering Drawing

Classification

Kingdom: Animalia

Phylum: Arthropoda (Invertebrate animals with jointed legs, segmented bodies, exoskeletons made up of chiton, a tough fibrous material often mineralized with calcium carbonate)

Class: Trilobota (Means three lobes or body sections. They are one of the earliest and most successful groups of artrhopods to appear in the fossil record with an estimated 22,000 species)

Order: Phacopida (Means lens face, these trilobites lived from the late Cambrian Period to the late Devonian Time Period)

Family: Calymenidae

Genus: Calymene (Small group of trilobites often found rolled up)

Species: celebra

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Check out my fiction books featuring factual prehistory insights blended with imaginative storytelling that entertain as they educate. Perfect for young explorers ages 11-15+ or young readers who simply like a good story, available on Amazon.com. Also available, a coloring/activity book featuring scenes from both books along with many of the plants and animals that lived during the amazing Devonian Time Period; fossil photos and descriptions included.