The shell is dull and often eroded or encrusted with barnacles. It can have rows of knobs (in sheltered areas) but most have little ornamentation. The aperture is usually dark purple trimmed with white but some can be bright orange.

in southern New Zealand this species is replace by Haustrum albomarginatum. Abundant in the mid tide zone of rocky shores. Most dense in oyster or barnacle zone.

Small and deadly, oyster borers force open the protective plates of barnacles with their muscular foot, and insert their proboscis into the flesh to consume it. When attacking shellfish such as oysters, they drill the shell with their radula, taking anywhere between 45 minutes to two days to reach the succulent meat inside.

NZ Coastal Marine Invertebrates; Vol 1