Bi-Valve ?

[shogun1964]

This thing came attached to a piece of LR from Gulf of Mexico. About a month ago it moved and last night I found it on the other side of the tank attached to a piece of base rock.
It's weird as the side opens and looks like a bird beak sticking out it's tongue, any ideas what it might be?

 

[qasim99]

Does look like a bivalve to me

 

[qasim99]

Does look like a bivalve to me

 

[KJ]

Bivalve.