Hey Steve...Thanks for the reply. I don't remember if the legs are jointed or not. I will have to keep an eye on that. I do know that it definately uses it's antennae for sensation when moving. It has moved all over the tank to different rocks. It has now been in one rock for about two weeks. I have some small bits of LR and some empty snail/crab shells laying on the bottom of my tank. It moved these to the hole in the rock that it is currently in and stuck them all to it with what looks like cobwebs. I pulled all of it away from the hole and it was all back there the next day. It hasn't messed with anything else in the tank, ie. coral, fish, crabs, shrimp, snails. I kind of have a problem though. I told my wife that if it keeps moving things around I would have to get rid of it. She said "You can't get rid of Peedy". That's what she named it. So I hope it's not too bad of a critter because I think I am stuck with it.