Crab ID help.

My tank is about 2 months old and I find something new everyday, it seems. It's like magic, and I love my new hobby.
I cant get a pic of this crab, but thought a good description might be good enough for someone to ID it for me.
The crab is a cream color. It's body is about the size of a pea (somewhat box shaped) and it's very skitish and fast. It's arms seem to have dark spots on it but the very tips of it's claws are a solid dark brown. It's other legs look a little hairy.
It's very hard to get a good look at him. When I do see it and try to move in for a good look... it's gone!
Any help anyone?
 
Hmm? I looked at pics of the white anemone crab. The crab I have isn't speckled on the body, just the arms. And not the whole claw but just the tips of his pinchers are a solid dark brown.
 
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