Distribution: Common in the Solitary Islands Marine Park. Known from Australia and northern New Zealand. Recorded on the Australian east coast from Caloundra in Queensland to Yorke Peninsula in South Australia, including Tasmania. Most common in southern New South Wales.

Ecological Notes: Found under rocks and in rock pools. Very common intertidally and subtidally to 25 m depth.

Additional Notes: Shell with rounded whorls and about 11 low axial ribs. Columella smooth, interior white with lip sometimes yellow. Grows to a maximum 35 mm length, commonly 20 mm.

References: Graham J. Edgar. Australian Marine Life, 2nd Edition, 2008. Reed New Holland Publishers. p.301.
The Seashells of New South Wales, Des Beechey, Senior Fellow, Australian Museum, Release 25. Website at https://seashellsofnsw.org.au/Rapaninae/Pages/agnewia_tritoniformis.htm. Accessed 16/10/2018.