Still new to the forums. I hadn't owned an aquarium in years and really didn't try to learn how to properly maintain one when I had it. I had 2 Oscars that thrived with daily feeding and vacuuming the gravel when the water looked dirty. So when my daughter asked for a new fish tank, I became very interested (always liked looking at aquariums). So we got a used 75 gallon, learned to cycle, went through the process of adding fish, had a few problems and lost one cory before I learned to do water changes more often, reduce the amount that we feed, and test the water frequently. Anyway, she saw a blue mystery snail a week ago when we went in to get another cory. We got the snail and added it. The snail was all over the tank within a day and continued to be active. She called me at work yesterday and told me that the snail was laying on its side, so she turned it upright with the net. It didn't move all day. When I got home, it still hadn't moved, so we thought it was dead (didn't know anything about snails). I got it out, put it in a ziplock bag, and went to an event that my daughter was in. We got home about 6 hours later and I started reading up on mystery snails to see if we did something wrong. Found out that they lay on their side sometimes, and they they smell really bad when they die. I took it out of the bag and it didn't smell bad. I put it back in the tank and it floated for 5 minutes. I read some more and found out that it may have an air bubble stuck in its shell. A few minutes later, it had its trap door open and its body was sticking out further than usual. It slowly sunk to the bottom of the tank. As we watched, 3 air bubbles came out of it. Then, it started moving all around the tank again! Sorry for the long post, but I thought this may help someone else. I almost discarded a live snail because I didn't take the time to read up on them, so hopefully this will help someone else in the same situation.