The fossil comes from the Bellevue formation in Ohio. Image via Wiki Commons This is Streptaster vorticellatus, a member of the Edrioasteroidea class. It lived “only” 450 million years ago, during a period called the Ordovician. The body plan for this class was simple: a main body (theca), composed of many small plates, a peripheral rim for attachment, and (in some species) a pedunculate zone for extension and retraction.
