I'm sorry is this post is somewhere else, I tried to post it before and then couldn't find it.
Found this fossil on Portland a couple of weeks ago and it's starting to annoy me now because I can't find anything like it on the net and really want to know what it might be. Any ideas?
Maybe an unusual section through the hinge area of a bivalve or brachiopod.
In such creatures, the two valves (shells) articulate in various ways, commonly including 'teeth' in various arrangements. Those teeth may stick up past the rest of the shell. What I have in mind is the shell being exposed (the surface of the stone) at a level that misses most of the shell, but shows the dentition (and in the case of a brachiopod it could also include some of the brachidium).
I can't find any really satisfactory images to illustrate this, but maybe these will help:
Other opinions welcomed...
I agree with Mike, I had not seen his reply until I posted and have also tried to find a on line picture,
this is the best I can do http://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/brachiopod.html
I have just one image , not quite similiar in one of my books, your fossil is cross section slice of a 3 dimensional shell showing the internal structure,
what a lovely find
Thank you for your reply's, and for taking the time to put links up too. Absolutely fascinating! We were all thinking it looked like bones.... Totally barking up the wrong tree :-)
It's quite big, the stone is about 7" across.
I see the superficial resemblance to graptolites - the toothed tuning-fork shapes.
However, graptolites were extinct (Carboniferous) long before these beds were deposited (Jurassic+),
and they tend to occur in deep-water slaty shales not shallower-water unlaminated limestones.