What is wrong with their shells? How to fix it?

Both of these mystery snails are new and have had weird shells. The first snail (don’t worry I only had him out very fast to take a pic) has a weird line that looks like it’s on the inside. Idk how to explain it but maybe his shell is too thin and transparent so I can see the actual snail? My second snail shell just looks rough and uneven. Both are very active but whenever they climb on the glass on the tank, they eventually fall down and I have no idea why they both do that. They’ve done it for 1-2 weeks. Just climbing to the top and falling all the way down