Eulimidae: Hypermastus mucronatus (G. B. Sowerby II, 1866) (‘pointed-tipped urchin-snail’)
Synonym(s): mucronatus Sowerby, 1866.
Typical shell-length 10 mm. Lives subtidally as an internal parasite of sand-dollars. Native. Endemic to southeastern and southwestern Australia (NSW, TAS, VIC, SA and WA).
Subclass: Caenogastropoda – Sorbeoconcha
Order: Hypsogastropoda – Littorinimorpha