This unidentified clam fossil found in the Waldron Shale of Clark County, Indiana. The fossil is about 1 cm wide and 1.5 cm long. Fossil is from the Silurian Period. This is only the second type of clam I have found so far.
Clam fossil embedded in some pyrite crystals.
[UPDATE: This fossil also looks like a Rochester Shale brachiopod found by the group at Primitive Worlds that shows up as Unidentified identification #11 on page 41 of their book.
My calling this fossil a clam has to do with the shell being asymmetric. Maybe this specimen has been deformed over time by geologic forces. One way for me to find out is to find another one.]