What kind of crab is this?

[rrmoore]

Hello to everyone. I found this dead in my tank this morning. My tank has been up for 7 months now. I never added this crab to my tank, so it must of hitched a ride on the live rock. I knew he's been in the tank for awhile, but she didn't seem to be causing any problems. Anywon know what it is? Thanks

 

[RG Rude]

I'm going to guess red mithrax crab but I will defer to those more experienced than I.