This whelk has a spiral shell with knobs (or spines) along its shoulder. The shell is up to 9.5 inches (24 cm) long. The shell is light gray to tan, and often has brown and white streaks.
On the shallow-water mud flats whelks prey on oysters, clams, and other marine bivalves. They wedge the bivalve open using the edge of their shell. Then they squeeze in their radula. This is a rough tongue-like organ that has thousands of tiny denticles (tooth-like protrusions).