A decayed Birch had given way and toppled into the water. I recovered what I could and a chainsaw worked the remainder. As I collected the shorts, I noticed that one bore the graze marks of a snail. Many gastropods use a toothed rasp to gather food. Grazing is highly ordered and elaborate patterns may accumulate on appropriate substrate. Look closely at any one of approximately fifty arcs of activity. More than a dozen feeding strokes are taken to the left, the animal moves forward, and as many strokes are then taken to the right. The behavior is reminiscent of what a cow might do on pasture … munch, munch, munch to the left, a step or two forward, and munch, munch, munch to the right.