rare-spined murex

Shells of Murex trapa can reach a length of 50–124 millimetres (2.0–4.9 in), with a diameter of 8–21 millimetres (0.31–0.83 in). These moderately large shells are fusiforms or club-shaped, with height and acute spire and prominent spiral ridges. Shell surface is normally light brown or blue-gray with some yellowish-brown on spines. The body whorl shows three spiny varices. The aperture is lenticular, with a white interior margin and deep red-brown within. The outer apertural lip is crenulated. The siphonal canal is straight and moderately long (about 13–47 mm). Three to four short spines are restricted to the basal half of siphonal canal.

This species is widespread from Madagascar and Mascarene Islands, South-Eastern India, Sri Lanka and the Andaman Sea to southern Indonesia, Philippines, Taiwan and Southern Japan.