Is this a genuine oyster fossil shell?

[Nothosaurus]

This piece was advertised as an oyster Fossil I would really appreciate any input on whether or not this is a genuine fossil, and would anyone know from what region it might have come from. It is being sent from Texas. Thank you so much everyone for your help and expertise.  The piece is 10 inches long.  The entire piece feels like stone.

Edited March 25 by Nothosaurus
Added description

[ClearLake]

Well it certainly looks like it could be a piece of one of our large oysters we have in the Cretaceous of Texas.  But it is just a fragment it would seem to me.  Those layered surfaces are fractured shell.  There is a Crassostrea species that  is very long and slender, but that appearance may be due to how this one is broken.

[Rockwood]

This is not the sort of piece that is likely to be a fake. 

[Ludwigia]

It's real alright, but it's nothing spectacular, being just a partial from something that is not all that uncommon.

[Doctor Mud]

Looks real to me.

I just found a complete shell from an oyster in New Zealand. You can see it here:

 

 

[ClearLake]

Yes, I should have added that there is no reason to think it is fake.  And I didn't mean to imply that it necessarily came from Texas, large oysters were pretty common in many places across the globe during the Mesozoic, I believe.

[Nothosaurus]

I want to thank you, all my dear, fossil friends, for your expert advice. It puts my mind at ease that this truly is a genuine oyster fossil shell. Perhaps from Texas. It is so wonderful to be able to come to the site and get expert opinions from passionate fossil lovers. God bless you all!

[FranzBernhard]

Very much looks like Crassostrea, but not necessarily of Cretaceous age.

Franz Bernhard