Monetaria moneta, Marshall Islands

Monetaria moneta (Linnaeus, 1758)
Money cowry, 12-34mm

The most abundant cowry species in the Marshalls, Monetaria moneta is found mostly on the intertidal reef, where the shells occupy reef pockets or hide under rocks, primarily on the seaward part of the reef. Some individuals, usually larger ones with more prominently knobby shells, are found on shallow subtidal lagoon interisland reefs and the tops of pinnacles. Others live within clumps of Halimeda algae on sandy lagoon reefs to depths of about 8m. Some specimens are adorned with a thin gold ring, but this is generally much less prominent than in Monetaria annulus, with which it may share the same habitat. The two species are easily distinguished by shape; Monetaria annulus has smoothly rounded sides and dorsum, while Monetaria moneta has some degree of lumpy knobs on the margins. Like the other common intertidal cowries, Monetaria moneta is often used in Marshallese handicrafts. This species ranges widely across the Indo-Pacific.

In the specimen photographed above and below, you can see the thin gold ring around the dorsal coloration. However, the knobby margins easily identify this as a Monetaria moneta rather than M. annulus.