Is this a fossil or what is it

[pipilo]

Sorry I don't know where this comes from exactly. It was found at an estate sale in Texas. Was told it was a part of a collectors pieces from Southwest U.S. and was presented as Native American. So far Native American people think it is a fossil so here I am asking your opinion. It's heavy, fits in the palm of your hand, has a noticeable single ridge on the humped side, has a hole in the top and a hole in the flatter side; is black in color with many grey channels or etchings on the humped side.  

 

In your opinion is this a fossil and if so any idea what it is of?  If it helps, it feels kind of cool to touch.  Thank you for your interest and time. 

[connorp]

Does not look like a fossil to me.

[grandpa]

Yes, it is a fossil.  It is a bivalve (think clam).  It looks much like the Cretaceous bivalves we find in Texas of the genus Cucullaea cf, blancoensis.

[pipilo]

Yes, Grandpa now that I see some photos of Cucullaea cf, blancoensis, (to me something like a Heart Cockle except without all the ridges). Used to seeing them with their colors (I collect shells) and not fossilized like this one. Many Kudos to you Grandpa.  It will go in my shell collection. 

[sharkdoctor]

+1 for steinkern of clam. Some examples for reference: https://www.cretaceousmantua.com/category/by-fossil-type/steinkern/

[jpc]

Just now, sharkdoctor said:

+1 for steinkern of clam. Some examples for reference: https://www.cretaceousmantua.com/category/by-fossil-type/steinkern/

yup.