oyster on the half shell

[masonh]

Picture does not do this fossil justice. Found today on a virginia tidal river shoreline. It is the oyster shell operculum with the actual oyster itself that was fossilized by mineral replacement. I've never found another piece like it.

 

[Harry Pristis]

There is a more-likely explanation than mineralized oyster softparts. This appears to be a steinkern -an internal cast- of the interior of the oyster valves.

The oyster was buried with valves closed. The softparts disappeared. The intact valves were infiltrated by very fine particles which hardened over a long time. Thus an internal cast of the space formerly occupied by the living oyster.

You can see many steinkerns in threads here. Commonly, they are steinkerns of gastropods (snails).

 

[masonh]

Harry, think you're probably right about it being an internal mold (steinkern) , the color of the sediment just happens to be almost the same shade as a liiving oyster, and the cast is attached to the fossil shell, looks good enough to eat, and they sure were big back in them days! i have actually found quite a few nice casts of clams in the same general area