Instead, they were moss-like animals belonging to the family of Fenestellida known for their fan-shaped, mesh-like appearance. In the process, their remains were released and consequently, the constant wave action of the lakes continue to deposit them on the beach where we love finding them!Īnother common beach find are Paleozoic Era "bryozoan" fossils, often called lace corals because of their delicately threaded appearance, although they were not true corals. I still wondered why their fossils are so prevalent on the beaches of the big lakes? Here's why: ten thousand years ago when the giant glaciers sculpted the deep basins forming the Great Lakes, they also dug into the deep layers of sediment where crinoid remains rested. Prehistoric fossilized remains have been discovered widespread throughout North America. Millions of years later, they fossilized.
During the "sea lily" crinoid's lifetime, much of the world's continents were covered under warm, shallow, saltwater oceans where their living species died and settled on the ocean bottom buried in sediment. I often wondered why so many crinoid fossils ended up along the beaches of the freshwater Great Lakes, especially since they had thrived in saltwater environments. Rendition of Paleozoic Crinoids Why Are Saltwater Crinoids Found In Fresh Water? Today there are far fewer species and most lack the long meandering stem common in Paleozoic varieties. Sea lily crinoid's lengthy history began during the Ordovician Period around 500 million years ago, although most fossils are from the Mississipian Period around 345 mya and are preserved in limestone. Crinoids fit into the phylum of Echinoderm, meaning spiny skin, and are cousins of starfish, sea urchins, and feather stars. Their loose structure resulted in the living organism's beautifully colored and flowerlike appearance which granted them the nickname of "Sea Lilies." They captured tiny food particles passing by on ocean currents with their feathery network of arms that functioned like traps.
Some varieties are known to have towered several meters in length. They were sessile creatures-in other words, they remained attached to the sea floor. They possessed branching arms that sat atop of long single stems. As living creatures, each circular section was stacked over another, constructing the animal's entire framework.
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