About four days ago I bought 4 mystery snails. Out of these, one of them was floating before I bought it, but since I'd heard that that was normal I didn't question it. But it's been 4 days and it has been floating nonstop (though it has occasionally stuck to a wall or a plant) and hasn't eaten anything. I tried putting it on pieces of blanched vegetables like cucumbers and zucchini several times, but it just crawled onto a nearby plant. Yesterday I also noticed that it started to stink. The other 3 snails seem completely fine, though.