This fossil appears to be an Ambonychia clam fossil with both valves. It is has quite a bit of matrix covering detailed parts. The clam fossil has a colony of cyclostome bryozoan (see this web site image or called ctenostome type on this web site).
The fossil still needs to be cleaned to see if more shell and bryozoan detail can be revealed. It is rare for me to find clams with both valves intact so this was a happy discovery.
The fossil was found in the Kope Formation of Carroll County, Kentucky, USA. These creatures existed in the Ordovician Period.
