Please ID this crab for me!

[aquariumgirl]

I took this crab out of my 10 gallon today, but I'm not sure if this is a good crab or bad. Please help ID this thing. Also, I found another crab in the tank, from what I can see, it's a suspension feeder (has feather like hands like an anemone crab) and it's green or green/blue. Does anyone know what this is called? I didn't take it out cause I didn't think it would harm anything in the tank.