Acquario di Napoli - Mediterranean Shame-faced Crab (Calappa granulata)

This was in the same tank as the last crab that I asked for ID on, and both were unsigned.

Yet again, I'm sorry for the awful photo - something to do with the small size of the crab, the lighting on the water, and the shape of the glass meant that all of my photos either came out blurred, dim, distorted, or all three. Here there is of course the additional problem that the creature has largely buried itself in sand!

I thought at one point that this could be a hermit crab and the other crabs in the tank were hermit crabs outside of their shell, but then I couldn't see any evidence of a tail on the other crabs which I think all hermits have. Does anyone have any insight on this?

@Ebirah766 thanks! I can see now the claws in front covering its face at the bottom, but would have never guessed they were claws.

Is this species (or even calappa shame-faced crabs in general) particularly common in captivity? I feel confident in saying that I’ve never seen one before…

@Kalaw
Pretty uncommon due to their aggressive temperament and cryptic nature

@Ebirah766 thanks again. Interesting if they're aggressive that Napoli chose to mix them with another (mystery) crustacean species.