They have a musk gland on top of their rump that produces a smell when they get upset.
B, Sole of the foot of Pyrula tuba, to show a, the pore usually said to be " aquiferous " but probably the orifice of a gland; b, median line of foot.
The gland has been found in both sub-orders of the Pectinibranchia, in Cyclostoma and Cypraea among the Taenioglossa, in Hemifusus, Cassis, Nassa, Murex, Fasciolariidae, Turbinellidae, Olividae, Marginellidae and Conidae among the Stenoglossa.
Thus the base of the gill passes in a slanting direction across the right-hand side of the kidney, the posterior end being dorsal to the apex of the gland, and the anterior end ventral to the right-hand corner.
There is a gland on the back.