Shell length to 15 mm; equivalve. Sculpture: about 14 strong radial ribs, each consist of 3 radial ridges; concentric growth lines give a frilled appearance where they cross the radial ribs and marginally; interstices as wide as ribs, with 2 radial rows of fine scales marginally; shagreen sculpture covers the shell surface; auricles strongly ridged. Colour: variable, usually white with radial pattern of black blotches on left valve; interior white, with external pattern visible internally. Habitat: attached under fallen coral plates on hard substrate. Distribution: Great Barrier Reef, central Queensland.