Beached shell of a 68mm specimen from W. Australia. The synonym tricostalis Lamarck refers to
three spiral ridges that run on the dorsum: the first, just above the suture, is a line of spikes (A); the second
is the row of tubular holes (B), and the last is a large crest between the suture and the holes (C).
Finally, a fan of sharp lamellae achieves to make this species impossible to confuse with any other.

The Staircase Abalone is covered by minute scales, especially along the dorsal ridge (C).
Colours and pattern remain constant. 3m deep, under rocks, Cervantes, W. A. 97mm.

92mm, West Australia. Spiral stairs on dorsal surface.