Well, I have a large apple snail, and sometimes he will go into his shell for several days, not moving at all. today when i got home he was floating in the current underneath my filter, just bobbing around. He was pretty much sucked into his shell. I was wondering, how can you tell if they are actually dead? Right now I am going to throw his favorite meal in to see if he goes after it, But other than that, i have no idea how else I could tell. Thanx