Fossil Identification Request

[Grover]

I found this object in a dry river bed near Waco, TX, a few years ago, and I have always assumed it was a fossil of some sort (especially since it was found near other verifiable fossils). I once sent some photos to a university paleontologist, but he just cynically dismissed it as a "funny shaped rock." Maybe it is, but there are things about it that don't make sense for a random chunk of rock. The cross-sectional shape is very concentric, and the smooth, regular groove is clearly not the result of random cleavage. Both of these aspects are very clear in the second photo, which was taken  along the "axis" of the crude "cylinder" the object seems to have been part of. Moreover, if you look closely, you'll notice that there is a cylindrical "core" of rock that has a different color (and maybe even texture) from the outer portion (almost, dare I say, like fossilized bone marrow -- but I may be letting my imagination run away with me there). Thinking it might be some sort of vertebra or other specialized skeleton component.  Anyway, I'd appreciate any insight someone might have about this "funny shaped rock." Thanks.

[Mark Kmiecik]

I don't recognize any fossil I'm familiar with. I think it's just an interestingly shaped rock.

[Grover]

Okay, then I concede the contest, but I still don't believe it's naturally occurring. I guess I'll shift my quest from paleontology to archaeology. Thanks for the reply!

[Brevicollis]

Believe me, in nature, all sorts of weird occurances are possible. Think of the six sidet pillars in Iceland, or the giant stone monument in the waters of japan, which all seemed to be archeological, but are natural. So this piece will most likely have a natural explanation. But who knows, it could be paleontological tho 

But i think this will remain a mystery forever.

Edited April 16 by Brevicolis

[Rockwood]

The creek bed near my house is loaded with burrow casts that have a groove running down one side. I think this is clearly a section of such a burrow. 

[Grover]

What is a burrow cast?

[Grover]

Actually, I think I can infer the definition. Fossilized "casts" (or sediment fills) of animal holes or burrows. You may be on to something there...

[Rockwood]

28 minutes ago, Grover said:

Actually, I think I can infer the definition. Fossilized "casts" (or sediment fills) of animal holes or burrows. You may be on to something there...

I took a walk out to look for some good examples to photograph. The creek bed is so grown over with weeds and algae that I settled for an okay example of a burrow, and I have some small casts in my collection. I'll try to post photos shortly. 

[Rockwood]

Well, here's a shot of a small cast. It will have to do for now. 

[Grover]

Thanks for taking the time to enlighten me!