Crinoids are known as sea lilies because they live on a stem and have a flower-like body. They are analogous to starfish with a stem. Although still existing but uncommon in the oceans today, they were very abundant in shallow tropical seas during the Paleozoic. Some Mississippian rocks contain so many broken-up fossil crinoids that the Mississippian became known as the Age of Crinoids. The most common crinoid fossils are the individual button-like plates that made up the stem. Crinoid fossils can be found in the Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian rocks of Kentucky.
The Mississippian crinoid Taxocrinus
Pterotocrinus from the Mississippian of Kentucky. The five large projections are spines that protected the crinoid from being eaten by fish. The smaller projections were arms that helped gather food particles floating in the water. The column would have been attached to the small circular scar at the center of the photo.
Coiled crinoid stem from Mississippian strata of south-central Kentucky. This may be Gilbertsocrinus according to Alan Goldstein.
Typical slab showing abundant crinoid columnals. The column is made up of hundreds of these columnal plates.