Good crab or bad guy?

[tzabor10]

This came with my Tampa Bay Saltwater live rock. Any ideas? Would you keep it? This is a molted carapace, the inside is still in the tank.

 

[Gumbies R Us]

I think that is a stone crab? (Could be wrong) if it is one, those can be harmful towards coral. Personally I would not keep it if I were you (assuming it is a stone crab)

 

[tzabor10]

I think you are right. So cool though. It carries mussels on a half shell like a cafeteria tray.

 

[liverock]

Stone crab...