Reasonable suggestions but:
- I would lean away from crinoid, as the internal cavities in the specimen are too large and the walls too thin.
Compare with the photo here - http://www.answersingenesis.org/articles/cm/v20/n1/lily-of-the-sea.
- I don't favour a straight shelled nautiloid, as the sutures would not be as simple; compare with
- And I don't think sponges or corals would show those 'horizontal' septa (vertical, maybe).
But there again, I don't have any better suggestions just now!
I do see fragments of what appear to be crinoid discs elsewhere in the specimen.
But I'm trying to be objective about the main fossil.
Yes - some info on locality and whether it was found in situ would be helpful.
Note: The tapered appearance may or may not reflect the 3-D shape; actually it may be parallel sided but cut at an angle creating the tapered effect.
Thanks for your suggestions.
It was found in wicklow, Ireland in some gravel outside my house. So it's origins could aren't certain.
Yep there are crinoid disks in the rock. And what I thought to be a shell on the back.
And I don't know if you can see in the picture but on one of those little white fragments there's a little golden spec.
Is that pyrite?
The golden spec might be pyrite; that's a good guess.
- tusk shell (scaphopoda) - early ones were straight, but none of them have internal septa/camera (walls/cavities)
- serpulid worm (Serpulidae) - tubular, but not right on several characters
- feather duster worm (Sabellidae) - ditto
- cirratulid worm (Cirratulidae) - ditto
- worm snail (vermetid gastropod, Vermetidae) - ditto
- tower snail (gastropd, Turritellidae) - divisions would appear oblique, and walls much thinner
- straight nautiloid (Orthoceratoidea) - some have simple septa, but even in those there is usually curvature (absent in specimen), and the cavities in the specimen are just too small (and walls too thick) (http://jpaleontol.geoscienceworld.org/content/83/5/664/F11.small.gif, http://jpaleontol.geoscienceworld.org/content/vol81/issue4/images/small/i0022-3360-81-4-714-f07.gif, http://jpaleontol.geoscienceworld.org/content/vol81/issue6/images/small/i0022-3360-81-6-1266-f05.gif, and this fine specimen - http://en.wikipedia.org/wiki/File:Sinoceras_China_01.jpg).
(In case anyone comes across this post in future, this diagram shows useful structural cross sections allowing discrimination between scaphopod, vermetid gastropod, and serpulid worms -
Thanks for the diagrams and photos. I think they'll be very useful in the future.
I found this in the gravel today. My first thought was crinoid but then I noticed it was different.
Could it be connected to the one from yesterday?
It's about 1 cm in length.
Thank you for all your help.
indeed, that could be crinoid (your first thought being correct). In some crinoid fossils, the 'gaps' that normally occur between discs actually stick out (like yours). That is shown in several of these specimens -
Related to your other specimen, you ask... No more than 'maybe'.
I have numerous almost identical specimens found not too far from Wicklow, down in Wexford so I assume the geology wouldnt be too dissimilar! I found them to be cross sections of crinoid stems, I will try and upload some pictures for you for comparison
Just to add, the geology in Wexford in mainly carboniferous limestone so theres every chance your find is something roughly close to that
Aisling - thank you very much - a most useful contribution - good job!
That pretty much nails the answer as crinoid (as per Polacanthus12's first suggestion).
If you have any photos of other views of the same crinoids, for instance showing the discs as circles/ellipses, and preferably in 3D rather than smooth cross-section, I would be interested in seeing them.
Also, if you have an idea of the name (even just the genus), do let us know!
This is proving to be a useful bit of education for me.
BTW, here's an excellent cast of a Carboniferous crinoid stem, the carbonate having been dissolved, leaving the silicious host rock. It shows the same inter-disc spaces as in your specimen, Ivan, only in 3D.
Being on Ebay, the image will disappear before long, but worth a look meanwhile -