Nerite snail alive or dead?

I awoke this morning to find my nerite snail not moving.It has a very strange shape.I thought it was dying and rotting inside it shells.And 2hours later I checked my tank again and it move to other location.Heres a pic :

 

If it moved or is attached to something, it's not dead.

 

Looks alive to me. But if he's acting lethargic, then something's up. Have you checked your water parameters? The snail may be reacting to something.

 

ammonia 0 nitrite 0 nitrate 25 ppm.How can I tell if hes acting lethargic?From the picture,is that normal behavior?

 

Snails like to play dead at times.

 

Yep. Mine are communicating their distaste for changing from gravel to black petco sand.

Just wait til they really freak you out by sleeping with their foot out!

 

The best is when they disappear for a week. And you take all the decor out, look thru the filter, then you start searching the floor and walls around the tank. When you finally wrote them off there back.

 

I see,one of the snail did really dissapear for a week,and suddenly appear out of nowhere,I never saw them leave the tank.They crawl until surface line and head back to bottom

 

Yea I heard a story (on fishlore) where a snail laid a clutch of eggs on the wall behind the tank. Another where a snail was walking on the floor below the tank. I never had 1 get out of my tank (the lid is sealed) . I have had them bury themselves in the substrate. I found him during my weekly gravel vacuum.

 

Yeah. I have 2 now because we replaced Harry (Houdini) after 3 days of searching. That was before I found out he liked to dig under the gravel. The day after I bought the smaller one Harry reappeared. Wherever he went though he took two of my rcs with him and left them there.