Modiomorpha pelecypod from the Mahantango

I have posted some specimens of Modiomorpha from the Mahantango formation before but this specimen is different in that there is some shell material preserved. It's not the original shell but more likely a replacement by Calcite.

The shell cast is not complete but this is still an uncommon occurrence from the Mahantango formation (Devonian, Givetian stage) since I often find the weathered, leached molds of pelecypods. This specimen came from near Liverpool, PA.