Crab?

[Lilxxwojo1]

I just found a little guy on the back of a rock I have not seen before. I think its a crab but I want to make sure... he seems to come out more when I turn off the light, has a hard body and not a shell, has smaller middle arms that he kind of flails out like he's scooping water, and moves sideways... I can't get a good enough look to see him but it appears that his outer legs have tiny bands on them and maybe tiny dots? I'll try and get a picture at some point but the only coloring I can see is a bit of yellow.... any ideas?

 

[herp_mommy]

Xanthid crabs are common. Try catching him. If he's safe you can always throw him back in

 

[Sniperhank]

If he has smaller arms that he is waving around in the water, I would say that this might be what you have. A picture would help out though.
Porcelain Anemone Crab

 

[kdpuffer]

It sounds like it could also be a Pom Pom crab without his "Pom Pom". A pic would help.