Hallo, I don't have a camera so I'm going to describe it as best I can. About two months ago I purchased some live rock for my new tank and to my surpise there was already a little animal within half an hour of being in the tank. He lives in what looks like a snail shell cemented to the rock (same color too), and near the top is an opening that literally "screws" open whenever the animal wants to poke his head out. There appears to be a mouth with a little tentacle on each side. I'm certain he has eyes because he reacts when I walk in front of the tank or wave my hands. When he's hungry he puts out a thread that catches any food or waste floating around in the tank, and then pulls on the string until the it reaches his mouth. Quite nifty. Anyway I've become very attached to the little booger and even consider him part of the "crew" I use to keep my tank clean. I even gave him a name, Marisco, which means "seafood". Any ideas as to what I've got?