Texigryphaea mucronata from Oklahoma

Texigryphaea mucronata (Gabb 1869)
From the Cretaceous,Cenomanian stage.
Collected from Bryan county,Oklahoma,U.S.A.
A very strongly ornamented Bivalve that thinks its a gastropod!
Preserved in a Dark cream colour,from the Grayson formation,Washita group.
Loose from matrix and measuring  42mm x  34mm.