Hitchhiker Crab ID: LiveAquaria Frag
 

Bought a large zoa colony (about 3-4 inches wide, 50+ polyps) and dipped in freshwater. Two very small crabs hopped off, both less than 5 millimeters in size. I had to pull out a macro lens just to get a decent close-up photo.

https://i.imgur.com/eD3DPOP.png

Any ideas? I looked through Chuck's Crab Hitchhiker guide but nothing was a definitive hit.

Gorilla crab? The lighting in your photo doesn't definitively show the black claw tips but the hairiness looks about right.