So i woke up this morning and found my black mystery snail floating in my 30 gallon bow-front. Thinking he was dead I scooped him out of the water. Wanting to be certain before I got rid of the body, I filled a small tub with aquarium water and put him into it. sure enough I came back and he was out a little. By a little, I mean that it pretty much looked like he had fallen part of the way of his shell. In any case I left him alone, and he just stayed that way, hanging half out of his shell. I was convinced that it meant the poor guy had died. I went to move the tub and to my surprise he went back into his shell. Currently he is half hanging out of his shell again? What does this mean? Is he sick? Is he going to die?