During a hike in the woods last Sunday, I saw some fungi growing at one end of a large dead tree on the ground. After I took some pictures of the fungi, I was about to leave when I noticed on the trunk what I first thought was a large nut. Then I realized it was not a nut but a shell of Neohelix albolabris, the largest land snail around here.
The shell was empty. The picture above shows it the way I found it, with its aperture up. I don't know how it ended up where it was. But I can think of 3 possibilities:
1. A person found it on the ground and left it there.
2. The snail crawled up on the log and for whatever reason died there. Eventually it rotted, leaving behind its empty shell. They do have a tendency to die with their apertures up.
3. A predator found it on the ground, brought it up on the log to eat it. Then, either it was able to pull the snail out of its shell without having to break it, or the shell was empty and the animal realized it and left the shell on the log.
At this point, your guess is as good as mine.