stowaway id?

[jojo_b]

I'm attaching a picture of a trio of crabs that arrived with my live rock, and am hoping to get some info to identify them.
The largest is about 1.5 inches and very compressed dorso-ventrally; very good for sliding into cracks in the rock, as I found out. They each have one pair of long whisker-like antennae. On the underside the large one is a purple-scarlet. The smaller ones are the same color on their backs and bellies.

 

[natclanwy]

Can you post a bigger pic I can't see enough detail.

 

[jojo_b]

This one might give more detail; when I try and make the other picture bigger, I lose resolution.
There's fringe on the front pair of legs, by the by.

 

[hlcroghan]

General rule of thumb is if they have black tipped claws they are not friendly. Are they hairy looking or smooth? Do they have sharp claws or flat ones?

 

[ryancw01]

I like 'em...throw them back in and see what happens...They kind of look like Pom-pom crabs to me, but it is hard to tell...they are reef safe...

 

[natclanwy]

This pic is a red mithrax how close is that to what you have they look similar to me.

 

[spanko]

+1 red mithrax. See those pointy claws..........through them in your fuge not back in your display. JMO

 

[natclanwy]

I was almost going to say that mithrax crabs were reef safe since emerald crabs are common CUC members in reef tanks but I did some reading they are oportunistic feeders and may decide they like soft coral. If were me and I had corals they would go in the sump.