what is this?

[TXRPLS]

i don't know what this is...i am guessing some sort of marine fossil. it's very lightweight. about 2.5" long... notice the very small lines running lengthwise.
-thanx

[TXRPLS]

well...you really can't see the lines...they are veeeery small running perfectly horizontal to each other. .  like straight strands of hair close to each other

[painshill]

The almost angular cross section and the dimple in the end suggest to me that it's a large sea-urchin spine which has suffered some weathering. These ones are not fossilised, but you can see the dimple (part of the articulation to the shell/test of the animal) rather more clearly:

[pic from shells-of-aquarius website]
"Spine" is a potentially misleading term since many urchins have/had appendages which were not sharp and pointed like most people imagine a spine to be. They're often "bulbous" and - if elongated - the far end may be fatter than the end that articulates to the shell/test.

[TXRPLS]

thanks!  i knew it was a 'spine' from some water creature...i just couldn't think of it.  but i found it in waco, tx.  across from the soccer fields in the spillway at lake waco.  it's also where the shark tooth in my avatar was found.  yer not suppose to go down there but i went down there a few years ago and found this and a tiny shark tooth.  a friend of mine found a shark tooth the size of a pack of cigarettes in the 70's.  it's near where the waco mammoth site is - about 2.0m wsw of the mammoth site.  they say the mammoths...and a saber tooth tiger (at different times) got stuck in mud and died...one adult mammoth is preserved oriented with its tusks trying to lift a young mammoth - to aid it in getting out of the mud.  pretty interesting.  it's near an oxbow in the bosque river.  so probably the bosque river was much larger back then and it was a lot wetter.  i suppose the whole area was once an ocean - hence the shark teeth that can be found nearby...  many many indian camps along the bosque river too etc. etc. etc.  another friend of mine said he saw a crab fossilized in the rock banks of a crab.  he could park his van on top of it and the van would not cover it up.  big crab!

[Bone2stone]

Your specimen does appear to be an echinoid appendage from a species cidarid. An echinoid "sea Urchin".
Roger is on the money.
Now as far as the spillway, the spillway has been off limits for many years. The pit area is another question entirely.
At one time you could get permission but since the 9/11 attack it is out of the question for a private collector.
I do have one thing to say about the shark tooth in your avatar.
It appears to be a great white tooth, possibly a Carcharodon these simply do not occur in the Del Rio formation.
The Del Rio is what makes up the strata of that particular site.
Is there any reason how that specimen was found there?
Jess B.