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.

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 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”.

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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