[KarenH]

What I thought was a hermit without a shell hiding in my rocks, turned out to be a small, hairy, brown crab. I think he came in on a piece of Live rock recently. I saw him slowly crawl out of a hole and move over to a different piece of rock this morning.

He looks a solid brown color, and is about the size of a nickel with claws the same size. He has hair all over his legs and the top of his shell as well. I'm worried that he will end up a danger to my colony polyps and other inhabitants. Does anyone have an idea on what he possibly could be?

[Ninong]

There is no telling what it could possibly be without a very good photo. It could be that this is just a juvenile or it could be that this is it's adult size. From your description, I suspect it's probably a juvenile.

There are some small commensal crabs that live with certain species of corals that are harmless but most true crabs are not welcome guests in reef tanks, especially as they get larger.

[KarenH]

Thank you for the advice. I'll try and catch the little guy and throw him in my sump. I'd rather not take any chances.