Just a little pebble

[Lone Hunter]

Calling this a Picasso pebble, it's like a tiny work of art and I have no idea how to refer to this type of fossilization but it's very cool. Anyway, really curious what the two columns are that appear to be joined, the gravels it came from are mostly Eagle Ford but include QAL, a little Woodbine, and older. 

[Carl]

My guts says that's an ammonite, but I think that would be unnaturally small. Maybe a foram? Great piece!

 

Update: Actually, I think snail is a good bet - you can see how the voids on either side of the midline don't line up perfectly, indicating a spiral.

Edited June 23, 2021 by Carl

[Lone Hunter]

Thanks! Wish it were bigger. I recognize the gastropod but don't know which way to go on the other one, esp since the two spirals join.

[minnbuckeye]

Looks like cross section of a crinoid stem: 

  Picture from Joel Knutson s

 

 Pi

[Lone Hunter]

Definitely one of my thoughts, I'm also trying to account for the object next to it that looks like a blank with just two of the balls/spirals.

[Carl]

4 hours ago, minnbuckeye said:

Looks like cross section of a crinoid stem: 

  Picture from Joel Knutson s

 

 Pi

That popped into my head, too, but I don't think that's it: the units on the side of the midline appear to be sediment-filled voids surrounded by what looks like shell. This would rule out crinoids. Plus, I don't think crinoids are know from this deposit (but I could be wrong there). 

Edited June 23, 2021 by Carl

[Rockwood]

1 hour ago, Carl said:

I don't think that's it:

Looks like a slight stumble there, perhaps a spot of rust, but he's recovered. 

[ChristineR]

So much happening on one little pebble. It is beautiful. 

[minnbuckeye]

On 6/23/2021 at 7:35 AM, Lone Hunter said:

mostly Eagle Ford but include QAL, a little Woodbine, and older. 

 @Carl 

A little older would bring in GlenRose which I think has crinoids. Seeing this is a tumbled stone, could this be possible? Does the matrix look right?

  

On 6/23/2021 at 12:50 PM, Carl said:

the units on the side of the midline appear to be sediment-filled voids surrounded by what looks like shell. 

 

Not sure what you mean. But when I look at it, I think I understand. I see tan in the center white, which I thought was crinoid, but it is the dark that would not be there if crinoid. The dark represents the shell??? 

 

Mike

 

[Tetradium]

8 hours ago, Lone Hunter said:

Thanks! Wish it were bigger. I recognize the gastropod but don't know which way to go on the other one, especially since the two spirals join.

100% cephalopod for #2 with the rattlesnake like piece. No gastropods have spirals like that. I have at least 2 species of less than .5 inch in diameter plus it can be broken tips of larger ones. Rest are gastropods. 

[Rockwood]

2 minutes ago, Tetradium said:

100% cephalopod for #2 with the rattlesnake like piece.

100% disagree. The sections are offset transversely. The oblique sectioning obscures the true shape of the end.

[Tetradium]

8 hours ago, Lone Hunter said:

Thanks! Wish it were bigger. I recognize the gastropod but don't know which way to go on the other one, esp since the two spirals join.

That's why I'm mystify why people think its a crinoid piece. You can see a very distinct tip, omitting crinoid, even tumor like growth ones. The first three are simple lobes then by the 4th siphuncle start (that's the void  in the middle). 

[Tetradium]

3 minutes ago, Rockwood said:

100% disagree. The sections are offset transversely. The oblique sectioning obscures the true shape of the end.

Cephalopods are very diverse in shapes of siphuncle. Simple as that. I have seen pictures of cephalopods with siphuncles thats offset, siphuncles thats very center located, cephalopods with siphuncle that looks like cones stacked on top of each other. 

[Rockwood]

59 minutes ago, Tetradium said:

Cephalopods are very diverse in shapes of siphuncle. Simple as that. I have seen pictures of cephalopods with siphuncles thats offset, siphuncles thats very center located, cephalopods with siphuncle that looks like cones stacked on top of each other. 

Putative siphuncle aside, the would be camerae don't line up.  They form a sectioned spiral. The end where they seem to form single camerae is too thin for the effect to be noticed.

[fifbrindacier]

11 hours ago, minnbuckeye said:

Looks like cross section of a crinoid stem: 

  Picture from Joel Knutson s

 

 Pi

 

3 hours ago, Tetradium said:

100% cephalopod for #2 with the rattlesnake like piece. No gastropods have spirals like that. I have at least 2 species of less than .5 inch in diameter plus it can be broken tips of larger ones. Rest are gastropods. 

 

3 hours ago, Rockwood said:

100% disagree. The sections are offset transversely. The oblique sectioning obscures the true shape of the end.

Maybe a marine worm ?

[Lone Hunter]

I appreciate everyone's input, though most of it is over my head. I thought this would be an easy one but apparently not. My first thought was cephalopods but since they joined I ruled that out. It almost looks like the spirals are growing out of the same 'base' so to speak. It is amazing how much is packed into this little pebble, it's like looking through a window into the past.

[Rockwood]

52 minutes ago, fifbrindacier said:

Maybe a marine worm ?

Don't know if it's possible or not. Maybe Carl will.

[Lone Hunter]

I surely wouldn't have thought worms. I have one more picture trying to show there is a slight chip in the pebble where they merge, I can see two more planes that have the same spirals also seeming to start at that point. Just in case that helps. 

[minnbuckeye]

I am beginning to agree with a spiral shell that Rockwood suggested. My question for you, as you progress longitudinally from the left edge to the right edge, is it flat or does the surface have curve to it? From my perspective, it appears to have curvature. 

 

Mike

[Carl]

16 hours ago, minnbuckeye said:

 

 

11 hours ago, Rockwood said:

Don't know if it's possible or not. Maybe Carl will.

Worm shells are rarely as organized as this one in my experience.

16 hours ago, minnbuckeye said:

 

Yes: the darkest parts would represent the actual gastropod shell.

[FranzBernhard]

Very good discussion!

I liked to contribute several times, but I can not decide what it could be.

 

Summary:

- Crinoid and worm can be ruled out.

- Gastropod. This would be one with the "tube" spiraling along a "void"? I am imagining a garden hose spiraled around something cylindrical or conical for comparison.

- Cephalopod. A straight-shelled one? Wouldn´t the spiral pattern rule out that possibility?

 

Well, I have a very small specimen which looks very remotely similar and I can also not make any sense of it. Hence my interest.

Franz Bernhard

[Carl]

3 minutes ago, FranzBernhard said:

Very good discussion!

I liked to contribute several times, but I can not decide what it could be.

 

Summary:

- Crinoid and worm can be ruled out.

- Gastropod. This would be one with the "tube" spiraling along a "void"? I am imagining a garden hose spiraled around something cylindrical or conical for comparison.

- Cephalopod. A straight-shelled one? Wouldn´t the spiral pattern rule out that possibility?

 

Well, I have a very small specimen which looks very remotely similar and I can also not make any sense of it. Hence my interest.

Franz Bernhard

"A garden hose spiraled around something cylindrical or conical" is a perfect description! I would only add that the hose tapers as it coils up the cone.

 

And I think we can easily rule out any straight-shelled cephalopod because of the time period.  Straight nautiloids were all gone by the Triassic. Ammonites were around, but the only straight ammonites would be baculites, which have a very different structure. Plus, the spiral in the specimen in question is in an entirely different plane necessary for a baculite interpretation.

 

 

[Lone Hunter]

Answer for curvature is no, the side with spirals is almost concave, on the picture that side is facing away from ruler however a slight dip on end  I think you can make out from side view. Edit, concave is curvature duh. The tips of spirals  slant down the rest of it is flat.

Edited June 24, 2021 by Lone Hunter

[FranzBernhard]

54 minutes ago, Carl said:

"A garden hose spiraled around something cylindrical or conical" is a perfect description! I would only add that the hose tapers as it coils up the cone.

Now we need just some extant or extinct 3D examples of such gastropods .

Franz Bernhard

[Rockwood]

Another option would be one that had its own covering of a material that preserves differently, or even an encrustation that spread with it as it grew. The second could be hard to duplicate under the best of conditions.