would you know what the snail would of came in on?, i have not added any new rock for about 2 years, all i added to my tank within the last couple of months were some frags. the body and underside of the snail look just like a limpet, but a diffrent color. that was the first snail i have seen that loked like that. he was on the clam shell and within minutes he was on the rock wich made it pretty easy to get off.
thanks
andrew