About Fragum unedo (Linnaeus, 1758)
Fragum unedo can reach a maximum length of 6.5 cm (2.5 in), though 4 cm (1.5 in) is the more common adult size. This species has two equal-sized, domed, asymmetric valves, with beaks located in front of the midline of the shell. The shell outline is sub-quadrate, with steeply sloping dorsal margins. The posterior margin is long and nearly straight, while the anterior margin is evenly rounded; these two margins meet at a distinct, almost square angle. The strong radial ribs of the shell often bear small red, thorn-shaped sculpturing, and the shell margin is deeply crenulated. The shell has a robust texture, and is primarily white in color, sometimes mottled with reddish mosaic-shaped patches. Fragum unedo occurs in the Indo-Pacific region, where its range stretches from Mauritius and Sri Lanka to southern Japan, Melanesia, and northern Australia. It is a benthic species that lives buried in sand or mud, from the low tide mark down to a depth of 60 m (200 ft).
