Harpactocarcinus punctatus

[Ezio Bonsignore]

I am very intrigued by this critter being currenty offered fo sale. It seems pretty obvious to me that the rock it is sitting on has nothing to do with the original matrix (and indeed, the seller's text does not mention thr world "matrix" at all). But then,  if the fossil has just been glued onto an appropriately shaped rock, how was it prepped to start with? Is it possible for crabs to get fossilised into such a soft matrix, that is it then possible to "free" the entire fossil completely intact, with all its legs, sort of Michelangelo's style (*)? And in any case, what technology and tools could produce such a result?

 

(*) Michelangelo maintained that the subjects for his sculptures were already present inside their marmor blocks even before he started working. on them. All he had to do, was to remove the superfluous material.

[Brevicollis]

Yes, crabs can fossilize in a perfect position, but often the legs brake off, so its pretty rare to find a perfect one whith complete legs. I think @mamlambo can tell you more about how crabs are prepped and what tools are used for it.

[Darktooth]

I personally have never seen a fossil crab outside of a concretion. To my eyes, it appears real. I actually really like how it is mounted to the matrix regardless if it in fact has any relation to the crab. For the right price I would probably buy it.

[mamlambo]

I've seem a few people completely remove the crab from the matrix to prep the underside and details easier before gluing it back on the original matrix. This little crab from Italy was done like that. I think it might be a similar species to the one you looking at.

As to how it would be done, air scribes if using pneumatic tools or pin vices if using hand tools. This video shows the process on a very large fossil crab I found here in New Zealand:
 

[Ezio Bonsignore]

Yes, the crab in my photos also comes from Italy, and looking at the photos posted by mamlambo I think I start to understand what is going on here.

The residual matrix in mamlambo's photos looks very much like solidified mud or soft sandstone rather than really hard rock. This would explain how it was possible to completely free the crabs without breaking anything , and also why the crab in my photos was not glued back onto its original matrix - it had all turned into dust.

I would certainly wish to know where in Italy are such things to be found.

[crabfossilsteve]

I agree that this crab was most likely prepped out of its original matrix and placed onto different rock.  The crab itself looks pretty dang good and I don't see any obvious reconstruction, even the legs look real.  Personally I would ignore the rock its placed on, however, too bad they couldn't have placed it on the host rock.