snaily and "Mo or less"

At what point do you tell your 4yr old that her pet snail, the one that she built a playground for, the one that gets fresh grass and dirt in its bucket each day, is now just a shell. She had two pet snails. They would get out of the bucket sometimes, but not far and then one day this one stopped escaping or moving for that matter. As far as pets go, it's a pretty sweet deal for Kap and me. Maybe in a couple of days I will throw it over the fence and tell her he made a break for it. Does that say something about my moral compass? Their names were Snaily and Mo. Snaily really did manage to escape with his shell. Mo, however, not so clever.