I've been keeping mystery snails in my tanks for the last year and they've done well. About 3 months ago I setup another 75 gallon tank. It has been stable for the last 2 months, with carpet plants starting to spread, and i've been adding a few critters a week, and am up to dozen dwarf shrimp staying healthy and active, a dozen healthy frolicking young panda corys, and 5 mystery snails that until several days ago were all doing well. The mystery snails were some of the first inhabitants of the tank.
However, recently I noticed one mystery snail hadn't moved for a few days. I picked him up and moved him a bit, and the next day he had crawled back to the same spot a few inches from I put him back in the tank. He's been in that spot for several days with his foot kind of extended oddly and on his side. I've picked him up each day to see if he is still alive. He seems to be, but I am just concerned perhaps it is ill?
All my tank values are good and stable, ammonia and nitrite 0, nitrates below 5ppm. ph is about 6.86. I do partial water changes once a week. Running an FX filter and UV filter during "daylight" hours for the tank, and automatic co2. I add crab cusine for them as a calcium supplement. I vacuum the bottom weekly, trim plants, etc. The tank water is clear, and the substrate is clean. No rotting plants, or other signs of issues.
Here's photos of how it has sprawled out. I've never seen this behavior in any of the mystery snails before now.