Unidentified Fossil - Maybe a Tooth?

[earthprime]

Below are pictures of a fossil we can't identify.  My father gave this to me in the 1990's, and the only story he told was that he found the fossil as a child, which would have been around Ohio.  We've never been able to identify what it is.

Edited September 11, 2020 by earthprime

[Rockwood]

Agatized partial steinkern of a bivalve. Some mold of the body of both valves remains. 

[Tidgy's Dad]

Pretty little chalcedony geode, perhaps? 

[Rockwood]

Just now, Tidgy's Dad said:

Pretty little chalcedony geode, perhaps? 

That too.

[earthprime]

It fits the profile of a fossilized clam, if I inspect the form of the larger cavity it does follow a clam-shape.  What throws me off is the small 'stem' coming off the 'tooth-shaped' piece, almost like a vertebrae.  But it could just be the way the valves of the steinkern came together on it's inside.

[Rockwood]

5 minutes ago, earthprime said:

It fits the profile of a fossilized clam, if I inspect the form of the larger cavity it does follow a clam-shape.  What throws me off is the small 'stem' coming off the 'tooth-shaped' piece, almost like a vertebrae.  But it could just be the way the valves of the steinkern came together on it's inside.

The internal mold portion of the steinkern indeed does show where the valves came together. That would be the "stem". The most internal cavity is just that, a natural cavity within the steinkern. The body fossil is a vacant mold.