The True Whelk (Colus Jeffreysianus) is a highly variable species of sea snail, exhibiting differences in colour and shell features. Typically, it has a spindle-shaped shell that can grow up to 60mm in length. The shell may have up to eight slightly rounded whorls, giving it a turreted appearance, with a sharp apex at the top. It is covered by a pale yellow, slightly hairy outer layer called a ‘periostracum’, which may wear off over time. The shell is predominantly white, though it may sometimes have a bluish or pinkish tint, and features spiral ridges and growth lines, contributing to its textured surface.

This species is found on sandy or muddy seabeds, typically at depths along the continental shelves, ranging from the North Sea to the North Atlantic and Mediterranean Sea. It feeds on small benthic organisms (organisms that live on or near the seafloor, such as smaller snails, bivalves, small crabs, polychaete worms, and other small invertebrates).