Gyrineum gyrinum gyrinum is a common and widespread western Pacific intertidal to shallow subtidal form, represented by huge collections of samples in all major museums. It is represented in 137 stations from New Caledonia; all except one are from around New Caledonia itself. The species is easily recognised by its large size (commonly reaching 30 mm high, and rare specimens up to 50 mm), its squat shape, its short anterior canal, its coarse sculpture with additional fine sculpture of low, narrow, closely spaced, axial costellae crossing all other sculpture, and its broad dark brown, bright yellow and white colour bands. The shell bears alternating, equally wide dark brown and bright yellow-on-white bands, six on the spire and six on the last whorl. The sutural ramp is white, with two rows of yellow nodules and yellow bands on the varices; below this is a strongly contrasting dark brown band around two rows of nodules, and half of the anterior interspace below them, forming a particularly marked brown band on the varices; below this is a single row of yellow nodules on a white ground on spire whorls, and on the last whorl a wide white band and two rows of yellow nodules, again producing a bright yellow band on the varices; below this again, a peribasal brown band over two rows of nodules and a brown anterior canal tip are separated by a white band bearing two or three rows of yellow to pale brown nodules. All colours are enhanced on costae and varices of most specimens, producing an obscure axial banding that crosses the more obvious spiral pattern. In life, the pattern is hidden beneath a thin, straw-yellow periostracum that bears closely spaced rows of closely spaced bristles, one row along the crest of each narrow, closely spaced teleoconch axial costella; the bristles are ca 1 mm long over most of the shell, but ca 3 mm long over the varices and prominent axial costae. The bristles trap much mud, and effectively disguise the shell (specimens observed alive in lunular hollows of Tridacna gigas, at Orpheus I. Queensland). The coloration is described in detail because it provides the sole separating character of the Indian Ocean subspecies G gyrinum wilmerianum . The protoconch has 2.2 whorls. G. gyrinum has been recognised with little difficulty since Linne's time, and so has received no synonyms other than the obligatory renaming in the individual "systems" of a few early authors.