I just got a 'queen conch' and yesterday it jacked one of my astrea snails. I woke up in the morning and saw them foot to foot, as if they were stuck toghether at the feet. When I came home from work, a hermit was in the snail's shell. From the pictures and the descriptions above, I think I may have a whelk and not a conch. It looks a lot like the top picture in Nate's post. Also the guy is never in the sand. it is either on the rocks or the glass, and has been since I got him (which is frustrating since I got him to clean the sand) Hmmm, I guess I will try to take a picture and post it on RC for an ID.