Ranging from the West central pacific and maybe Indian Ocean. Intertidal to about 60m on reef rock beneath dead coral, sand bottom with algae, and on coral and rubble. C. planorbis is not distinguishable from C. ferrugineus by size and shape of the shell. The only reliable difference is the uniformly white aperture of C. ferrugineus, in contrast to the violet to violet brown base of the aperture in C. planorbis. In addition, the white sub-shoulder band of C. planorbis rarely occurs in C. ferrugineus, and the granulose ribs on basal part of last whorl are often light coloured in C. planorbis but usually overlaid with a dark spiral line in C. ferrugineus. The violet colour of the basal end of the shell most pronounced within the aperture is a distinctive character of this species.
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