Help with hitchike Crab. ID

[vheung]

HI guys,

New here. I bought live rock from a guy in craigslist and found this guy late at night. It's pretty big (relative to some of the fish I have) and wanted to know if they will live in peace. Do you guys know what kind of crab he is?

 

[Sugar Magnolia]

Looks like some type of stone crab. They can be very destructive. If you have a sump you can toss it in there.

 

[vheung]

I did a lot of googling. The pics seem like it's a convex crab. Bad thing is if it is that then those crabs get pretty big.