New crab? ID?

[Damsel13]

Hi all, I just got a new live rock a couple of weeks ago. I got it from a place that has tons of LR near LAX. Anyway I found this crab shell the other day along with one claw. I could not get the claw out but it was, including the arm part as long as this shell.
Any ideas if this crab molted or do you think it got eaten? I have a strong suspicion that I have a small green mantis in my tank. I saw it about 18 months ago and heard it about 8 months ago clicking but I haven't seen it since. It was about this long ------------------ then and rather translucent matching the macro algae in my fuge (then it escaped through the return and ended up in my display)
Here is a picture of the crab shell.

 

[NaH2O]

I would wager that is a Xanthid crab. Nasty buggers. Stick him in the sump, or find someone with a large mantis to take it off your hands. My sister's tank had one eons ago, and at night it would come out of the rock and grab pincerfulls of detrivores to eat. It took alot to get it out of its hole in the rock.

 

[Damsel13]

Oh *sigh* that is not good news. Last night I put out some meaty food to see if I could entice the suspected mantis from it's den which I can't find. Don't know for sure if it is still in there. No luck. Maybe I can get the crab though. Thanks for the info. NaH2O.