Came downstairs this morning to find the shell of my mystery snail completely empty. It took a while but I found some remains stuck to the back of the filter. There was about a 3rd of a chewed up body left.

I immediately checked the water and ammo-0/nitrite-0/nitrate-10. I dont think any of the fish could have pulled him from his shell unless he was already dead. Do mystery snails ever vacate shells of their own accord?