Pair Of Edrioasteroids (Hemicystites) - Kinkaid Limestone, Illinois

This is a pair of unusual fossil Edrioasteroids (Hemicystites sp.) fossils collected in Johnson County, Illinois. They are Mississipian in age. From an old collection.

Edrioasteroids are an extinct class of echinoderms that lived from the Ediacaran until the Permian, about 300 million years ago. The living animal would have resembled a pentamerously symmetrical disc or cushion.