Selection of gastropods commonly found in rockpools, clockwise from top left: Periwinkle (Littorina compressa / nigrolineata), Dogwhelk (Nucella lapillus / Thaius lapillus), Common Flat Periwinkle (Littorina obtusata), Purple Topshell (Gibbula umbilicalis), Edible Periwinkle (Littorina littorea) against white background. From the Isle of Skye, Inner Hebrides, Scotland, UK.