a few weeks ago I bought a mystery snail and a nerite snail for my 20 gallon. The first week the nerite was super active, the mystery wasn’t. Now the mystery is SUPER active and the nerite never moves. The tank has been cycled for almost a year, and there’s lots of variety of algae. I’m positive he’s not dead, when I move him he’ll start moving about an inch or two. The gravel is smooth, so I’m sure he’s not in pain from it. Ideas? My oldest betta lives with them, but never bothers them, so he’s not doing anything. My past nerites were kind of like this, the red racer I used to have never moved either, except a bit, and the tiger was very active.