The snail in the center of this image is climbing on a standing-decaying leaf blade of smooth cordgrass in the morning, before dew has had a chance to dry. Periwinkles probably climb up shoots for more than one reason, but the one on which researchers have focused is predation escape -- the snails try to stay above the rising tide and its attendant predators, especially blue crabs, which crush and eat periwinkles. Another reason to climb, probably the predominant one, is to find virgin patches on standing-decaying leaf blades. The sparkles seen in the background in this image are from the bare sediment; the tide was not on the marsh. Climbing is enabled by any wetting event (dew, rain, tides), and permits the snails to reach new food sources (less-grazed patches of fungi).