 By looking at the composition of aragonite in the growth layers of mollusks you can predict the size the mollusk shell can reach.A number of species of sea snails are used by humans for food, including abalone, conch, limpets, whelks (such as the North American "Busycon" species and the North Atlantic "Buccinum undatum") and periwinkles including "Littorina littorea".The shells of sea snails are often found washed up on beaches.