Brachiopod shells are probably the most commonly collected fossil in Kentucky. Brachiopods had two shells and lived attached to the sea bottom or some object on the sea bottom.
Although they had two shells or valves, as clams (pelecypods) have, all similarity ends there. The internal structure of brachiopods is entirely different from that of the clam. Brachiopods still exist today but are very rarely found as seashells on the beach. However, in ancient Kentucky, they were very common and far outnumbered the fossil clams and snails living in the sea. Brachiopods can be found in Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian rocks in Kentucky.