Need help IDing from Post Oak Creek.

[Austin83]

I found an abundance of these small similar shape and size objects in Post Oak Creek in North Texas.  Any help is greatly appreciated.  Thanks in advance.  

[Tidgy's Dad]

Looks like what in the South West of England used to be called "calcite beef". 

[Thomas.Dodson]

34 minutes ago, Tidgy's Dad said:

Looks like what in the South West of England used to be called "calcite beef". 

Haven't heard that exact terminology but I get what you mean and I agree with the ID.

[JamieLynn]

Could also be fragments of Inoceramus clam, very common in Post Oak Creek. 

 

[Fossildude19]

Or pieces of rudists.

[Thomas.Dodson]

1 hour ago, JamieLynn said:

Could also be fragments of Inoceramus clam, very common in Post Oak Creek. 

 

For clarity to OP, Inoceramus shell layers are calcite so they have that distinct prismatic layering.

 

Since Inoceramus are common in the area I'd guess Inoceramus is more likely. I see that calcite patterning much more often in Inoceramus than ordinary calcite.  What's the size of the pieces? One other thing to look out for is that in Inoceramus the prisms tend to occur in layers in thicker individuals.