Found In A Bag Of "river Rocks" Bought At A Local Menards Store - Care To Take A Crack At It?

[smokeyjoe]

I found this fossil in a bag of "river rocks" that I bought at a local Menards store, hence I have no idea where it was orginally picked up. I'm not knowledgeable abuot fossils and don't know if this is a plant or animal, but I'd sure enjoy knowing what this is! Can anyone identify this?

Thank you in advance!

[JimB88]

looks to be either a partial cephalopod or maybe a crinoid stem section..both are animals btw.

my money is on the cephalopod..seems to show a siphuncle.

Edited April 27, 2015 by JimB88

[TNCollector]

Looks like the stuff I have found in the Citronelle Formation. I would put my money on it being a crinoid stem.

[jpc]

I vote crinoid stem section. If you look at the right edge of the rock, there seems to be another one there, seen as a ring, which has not eroded.

[abyssunder]

...Crinoid stem +1

[Nandomas]

...Crinoid stem +2

[snakebite6769]

Crinoid stem +3

[the tatter]

Has anyone considered an archimedes? because the lines seem to be curving.

Marilyn

[TqB]

I think I vote for cephalopod! - looks like a septum at the bottom bending back to meet the previous one, making part of the outer shell.

I agree the other ring shaped section on the right looks like crinoid - no reason why you can't have both though...

Edited April 27, 2015 by TqB

[Manticocerasman]

I’m also more inclined to identify it as a cephalopod.

[smokeyjoe]

This is all immensely interesting! Thanks to all who have posted so far. (And I certainly welcome additional replies as there seems to be at least a few possibilities.) I have already learned about crinoids, the Citronelle Formation, siphuncles, Archimedes, and Cephalopods. I don't know if its significant or not, but if you look at the LEFT side of the riock, it almost looks like a ball perched on top of what, for now, I'll call the "stem", although that could just be the shape of the rock, and not a part of the actual fossil, I suppose. If it is a ball, would that suggest anything?

The ring on the right mentioned by two posters is very sharp and distinct when viwed from that side. My uninformed eye thought nothing of that...until it was mentioned by knowledgeable members of this group.

Is there anty way to be definitive with the ID, or is ambiguity more the rule than the exception on something like this?

Does anyone want a photo from another angle?

Thanks again!

[TqB]

I was wondering about the ball - it could be the infill of the start of the living chamber, assuming it's a cephalopod...

See the picture at the top of the Wikipedia article:

http://en.wikipedia.org/wiki/Orthocone

Edited April 27, 2015 by TqB

[Auspex]

What appear to be septa are curved. I think it is a cephalopod.

[jpc]

Is there anty way to be definitive with the ID, or is ambiguity more the rule than the exception on something like this?

You could get some latex or silicone and make a mold of the negative space. That would give us a 3d view of the thing as it was. But it is a lot of work...

[smokeyjoe]

I'm willing to try. Is there a sticky somewhere or can simple directions be provided to show me how to do that?

[PennyT.]

Fun project and interesting discussion.

[Auspex]

[TNCollector]

Could you take a picture of the fossil without it being slanted? As in, a picture from the top of the fossil. I feel like the rings only look curved because the angle of the picture is making it look that way. I am still thinking crinoid.

Edited April 27, 2015 by TNCollector

[Scylla]

I have to chime in on the side of cephalopod. The siphuncle looks to be off center and the septae are curved, both would not be true if it were a crinoid segment. The smaller ring does look like a crinoid segment.

[smokeyjoe]

Here's a new photo taken from a different angle to better show the curvature.

[erose]

Definitely cephalopod.

[Rob Russell]

It certainly resembles many cephalopod pieces Ive found in some local Silurian aged dolomite. Where I have yet to find anything crinoid.

[TNCollector]

After seeing the new picture, I agree, it is a cephalopod.