Colus pygmaeusColus pygmaeus, common name the pygmy whelk, is a species of sea snail, a marine gastropod mollusk in the family Colidae, the true whelks and the like.DescriptionThe length of the shell attains 23.9 mm. The shell body is dextrally coiled.DistributionThis species occurs in the Northeast Atlantic Ocean. Colus pygmaeus is currently undergoing steep population declines, which has already led to, or if unchecked is likely to lead to, local extinction and/or range contraction.