Need An Opinion For My Snail

So my black snail hasn’t been very active for more than a week now (maybe two), doesn’t have anything changed in the tank at all but the regular weekly 20% water change. All ammonia nitrate pH all good. The white mystery snail is doing fine and active so just the black one. I thought maybe it’s just because he’s active in the night but nope, woke up couple times in the middle of the night and he doesn’t seem to be moving. He likes to be where the bubblers are and likes to be on the edge of waterline alot lately (not usually). When i put in the food he usually do the back flip thingy and spread his feet or at least chase after the algae wafer but no more, not even the peas or the romaine lettuce. I’m very concerned, I had him since December 2017, is he just getting old? Is it the season? Is he dying?

All the other fishes are fine and the other snails too, it’s a planted tank with bubbler put in.
Doesn’t notice any crack in the shell either looked normal, can be seen the white snail on the bottom eating algae wafer

 

Sometimes snails will stop moving for long periods of time, if he is sticking on the side of the glass then he is most likely fine and will go back to normal shortly.

 

Awesome thank you!

 

No problem While it's not impossible your snail would die, your snail is most likely just exhibiting normal behavior.