Sunday we took a hike through the Douglas firs and madrone growing near the Oregon Caves--and this is one of the snails we found. It's endemic to the area, about a quarter size of my fist, and bright red. I heard a park ranger say that the snail eats the moss growing around here. Since the mountain the caves are in is made up of a lot of marble, the moss has a high concentration of calcium in it. The snail gets so much calcium its shell is extra thick and sturdy.