Jacksboro Tx Site Mystery Fossil - Id?

[Wrangellian]

I have seen burrows lined with similar patches of slickensides but this looks more like shell or bark, right?

Reminds me of Calamites stem too but I guess if there were any chance of that you would have considered it?

[Missourian]

Also, it's strange how the 'shell' material is fractured and separated as if the cylinder was had been stretched from the ends rather than merely flattened as one would expect with a crushed shell. It's as if the sediment inside had expanded.

[Roz]

I don't see any encrusting fossils on my specimen.

[Rockwood]

Also, it's strange how the 'shell' material is fractured and separated as if the cylinder was had been stretched from the ends rather than merely flattened as one would expect with a crushed shell. It's as if the sediment inside had expanded.

If marine animals and terrestrial plants are both being considered it seems possible that an influx of fresh water caused the expansion by the same principle thought to be involved in the formation of syneresis cracks.

[erose]

My understanding is that these are coprolites. But boy-o-boy I wish I could tell you where I learned that. Messing with my identifications again...