Shells small (Gyrineum) to large (Cymatium), operculate, heavy, with whorls bearing up to 2 varices, these being rarely connected to those of adjacent whorls. The lack of spines and scales prevents a confusion with some Muricidae, and the periostracum, always very furnished when it is present in a genus, is an other characteristic of the family.
 

Shell medium-sized, thick, solid; whorls cylindric, with a large subsutural ramp, more or less sloped depending of the species; primary sculpture of strong spiral threads crossed by radial costae, bearing, between the shoulder and the suture below, marked nodules at their intersections; secondary sculpture made up of very weak to strongly carved growth marks; periostracum brownish, like an epidermis, with occasionally hairy bands along some of the varices.
 

« The Monoplex has one fold on its body; the Biplex two folds; the Hexaplex six folds… » – G. Perry: Arcana, or, The museum of natural history London 1811, p.87 (Conchology, Triplex). Aperture and columellar callus extremely folded.