The smooth periwinkle, Littorina obtusata, is a brightly colored native of Maine shores. You'll find this tiny, flat shelled periwinkle living among the brown algae. They are not nearly as numerous as the common periwinkle. They prefer to stay as close to the water as possible so they are found in the lowest reaches of the lower intertidal, often under the canopy of algae. It is able to survive some extremes of exposure and temperature, but it is not nearly as well adapted to being out of the water as the rough and common periwinkles. L. obtusata grazes mostly on the Fucus type algae as well as Ascophyllum.

While you can find the bright yellow shells like the one pictured above, L. obtusata has many variations in shell color, ranging from green to brown to orange.This color variation may offer some camoflauge in the seaweed canopy, the smooth periwinkle often masquerades as the seaweed's air bladders.