Crinoid Fossils

Crinoids first appeared in the fossil record during the Ordovician Period, 490 million years ago. While they resemble plants, crinoids are actually a type of animal, functioning in a very similar way to modern and ancient corals. Their large stems would be rooted into the substrate or stuck to rocks, while their “fans” would float above in the water, filtering out plankton and other microorganisms.