I like Michelle's comment, yay animal lovers! We accidentally brought home a crab from our honeymoon in cuba, and we immediately invested in a salt water tank to keep him alive, when we got live rock we ended up with hitchhiker crabs as well, when we had predatory crabs then we just didn't get fish, and our tank was boring ha ha, well we like it, we've had one hairy reddish brown crab with white stripes on the legs and pointy claws for a while, and tonight we just noticed a black red eyed crab that has had to be there for a while, sounds like the same you are describing on this forum right now....a while ago we had a smaller beige crab, about nickle sized, and then one day he was in peices and we assumed it was his skin he shedded or was eaten by "Harriet" (the reddish brown one) but now that we've discovered this black one maybe he did it, Harriet is quite social, but all the others were always quite elusive, i've seen the tips of claws in another hole, and i'm never sure whether its Harriet or now this black one?... Anyone know what any of these crabs I've described are called?