I had a Zebra Nerite get out and go for a walk, er, a slime? I looked around but there was no snail to be found for a couple weeks until we removed our stove to install the new one and voila! 1 Zebra Nerite dried up under the stove.
My Tiger Nerite is fine, he hangs out around the water line a little, but never seen him above it, even when we put him in my wife's betta tank for a couple days which only has about 3" of water in it (trying to breed Bettas).
I have nerites crawl out without me finding them for a week or so, and they have been perfectly fine after you put them into the water. They completely shut themselves closed if that happens and can last for quite a while.