Brachiopod interior?

[Rosemary]

I was wondering if this is a brachiopod interior, and if so, could it be rafinesquina?

[Rockwood]

I think that's an exterior surface.

[abyssunder]

I'm thinking, it's the internal side of a brachiopod valve, partially ecrusted by bryozoan, but I could be wrong.

[Mark Kmiecik]

I only see bryozoan, but I'm not an expert.

[westcoast]

Search for Pulchratia symmetrica brachial valve interior for something similar.