So, I'm thinking that my Mystery Snails bit the dust, but not sure. We've been having an issue with Ammonia in our 75g tank last few days, and we "thought" we could see movement from the snails, but just now I took both of them out and one has a smell. The other doesn't, but when I poked at his underside I got zero reaction. Does it take a while before they begin to smell? How quickly could they skyrocket the ammonia level if they had been dead a day or so?