Acro Crab ID?

[Catastrophi]

Just bought a nice tenius colony and found this crab on it. It's not the normal white and black crab I've seen before so I wanted to double check. The colony doesn't seem to have any damage on it so I figured it might be safe?

I'm talking about the top crab.

http://img.photobucket.com/albums/v608/rice4life4o9/939b9ebc-1.jpg

[SKremk]

Yeah, the crab at the top of the photo looks like a Trapezia crab, which are fine. The other guy looks like trouble!

[dzhuo]

The top one is Trapezia digitalis (which should be harmless). The bottom one is Cymo andreossyi (which generally mean trouble in a reef tank).

[Catastrophi]

Yeah. I've seen threads about the bottom one, but I wasn't positive about the Trapezia digitalis so I figured I would ask you experts!