I just found what looks to be a baby snail on one of my live rocks. I will try to get a picture, but it is pretty small, and my camera is not very good. Anyway, it looks a bit like a Nassarius shell, but is up high in the tank on top of rock. I do have some of these that live in my substrate (only come out at feeding time). Are they known to breed in tanks? I haven't added anything new to the tank in about 4 months, so between the look and ?, I am thinking it might be them? Any ideas?