I find it real funny why sometimes my snails bury themselves in the soil and sometimes they sleep upside down on the ceiling. I don't think it's the moisture levels of the soil because they do it on and off, like one day they bury themselves, the next day they sleep on the ceiling them the next day they bury themselves again? Confused!?
My snails like to sleep upside down too ;D While I haven't found them on the tank's lid in awhile, it isn't uncommon to find them there every once in awhile. I have smaller species so more often than not I find them on the underside of the fake ivy I have in the tank.
You may want to keep an eye out for eggs if you don't already, as they do bury their eggs.
I think (though it's just my own thought and may not be the correct theory), that it has something to do with a snail's instinct to hide when resting. Sleeping upside down under something in the wild is often done under a rock, or log etc. It would be a sheltered spot out of the extremes of weather and away from the eyes of hungy birds. Therefore I would suspect that the snail is just finding a way of sleeping under something - i.e. under the lid of the tank.
Mine have individual preferences, ranging from the lid, to behind artificial plants, to under artificial logs. Some bury but most of mine don't.
I agree with Crossless too, temperature may have something to do with it. It may be warmer up near the lid, they'll often go to where the right temperature is.
I think it's something to do with their natural instinct to climb and bury. It's not a problem or anything to worry about. I found that when I added sticks and things to climb on in my snails enclosure they spent time on each of them.
My snails are like that as well, they either sleep on the roof of the tank, or on the walls. They kinda dont bury that much at all strangely enough, only partially when they are sleeping Sometimes I even find them sleeping right in the open substrate so to say. Makes me wonder if they instinctly know that they are free from danger
I'm not dumb, I'm just having bad luck when thinking
My snails were sleeping on the ceiling until I started placing large hosta leaves and other large leaves with the stems pushed into the soil so the leaf is up now they sleep under those and that way all the poop is under the leaf and when the leaf starts to go I just toss it and put in another. I was thinking I should get them those little cocktail umbrellas. LOL
3 species unidentified slugs