I have no idea. Could it be a fossil? The inner portion of a mollusc's or snail's shell? Is it an artifact? A part of some commonplace, modern day contraption, or maybe an ancient tool?
I can tell you that on close inspection, it seems too symmetrical and contrived to be natural. It looks machined, but for what purpose? There is a very fine threading, suggesting an embedded screw, in the middle segment. But the "screw" seems to be made of the same material as the rest of it. On the whole, it looks and feels like natural river rock, tumbled smooth.
The Prize: In hopes of spurring you on to great feats of scholarship on this matter, I propose to award the producer of the most plausible theory of origin for this item One Year's Free Subscription to this blog!*
*Must be present to win. Not valid in all States. Prize to be received via hyper-text transfer protocol only; the receipt of no material goods is implied by the rules of this "contest."
8 comments:
Hi Matt,
Since you imply that's its a river rock and since the rock doesn't look like limestone, it looks more like sandstone, it's a good bet that the screw-like structure is not a fossil. Limestone doesn't typically survive for very long in high energy river type environments that would tumble them smooth, and fossils are rare in non-limestone formations.
My guess is that it's some sort of manmade tool, maybe used for processing some sort of natural fiber like yucca or root fibers of some sort?
Paul
As good a guess as any so far, Paul. My new (today's) theory is that this might be a chip of conrete or some other manmade "rock," that happened to find its way into a stream bed or other process that tumbled it to a natural-looking state.
If that's the case, this interesting screw-type feature in it might be the impression of a small fastener or other construction device that fell into the concrete as it was mixed.
Later, when the concrete chipped, the original piece might have fallen apart and out of its setting, leaving the impression like a mold.
So, if all THAT'S possible, what sort of fasterner is this the impression of? What sort of concrete would weather into a natural-looking skipping stone?
Any hard hats in the audience?
The more I look at it the more I want to vote for crincoid stem.
http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/crinoid-20.jpg
I'm not sure, Reid-- the one you link to looks just like the ones I find across the river, but Matt's is different (and way smaller). And what about Paul's caveats?
OTOH Matt's newest theory sort of surpasses Occam's Razor!
Steve and Paul, I'll bring it with me. You can take a look for yourselves. :-)
My first impression was crinoid as well, but usually there'll be lots of visible crinoid stem cross sections on the surface of the rocks which contain them. Now looking closer it's tough to say if that's sandstone or limestone, I have some HCl laying around at home we can do the fizz test when you come by next week.
Matt
I vote for crinoid stem. One of the fun things about Louisiana is being at the end of the Mississippi River flow. We have rocks and gravel from everywhere upriver, washed smooth by thousands of years of flow until finally dug up from some gravel pit for construction. Sometimes intact stems over a inch long can be found. Glad to see your daughters have discovered this southern tradition, everyone's driveway is a fossil safari.
Have a great trip,
Russ
Russ
I can totally relate. I spent my youth fossil hunting in driveways in Arkansas and Tennessee!
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