Various sizes of the Platystrophia brachiopod from the Ordovician Period. The ruler scale is in centimeters. They are good size fossils ranging from 3-4 cm in width. These specimens were found east of Louisville, Kentucky in the Grant Lake Formation. Quite a nice looking creature to be the official fossil of Kentucky.
This is an articulate brachiopod in the order Impunctate, superfamily Orthacea.
It is possible the species is Platystrophia ponderosa but don't hold me to that identification, Hoss (or is it Little Joe). See more examples of this type of brachiopod at the Dry Dredgers of Cincinnati, Ohio webpage.