The guy at the LFS said it does not have a hard shell - it is not calcified or anything. He also said it must go on the substrate and that my CC is OK as it eats detritus in the substrate. It has a softish grey tube and then at the end of that is, I guess, the worm covered in substrate. My question is should I bury the worm part, or just leave the whole thing lying on the bottom? I'm thinking just let it lie on the bottom and it will figure itself out in a few days. LFS dude said it can and will move around as needed on the bottom, but that it's not agressive nor strong enough to move anything. The less I mess with it the better, of course. For time being, it's just lying in tank (since yesterday). I will get a pic when my camera charges.