Texas interesting fibrous looking

[NiNjA]

Found in Texas between Arlington and Fort worth while cleaning up flowerbed. Dug out of ground.  Must have pulled out 100 pieces or so.  Didn't get all that was there. Wish I could have.  Most pieces look to be ammonite fragments but a few just struck me as odd and do not seem to fit into that category.....

[Pemphix]

Looks like some kind of reef debris. I don't see any bones or boney structure here.

[JohnJ]

Indeed...most of these pieces are chunks of a caprinid rudist reef.  The linear structures are one of the typical characteristics.

 

Within these reefs, the bivalve, Chondrodonta can be common.  This looks like a fragment.