The shells of this family have a polished highly patterned appearance. All have strong axial ribs. A flaring lip on the final whorl dominates the flattened spire. The family has less than a dozen species.

The Harpa mollusc shares much in common with volutes and olives. All three families make up the Volutacea superfamily, all of which are active, carnivorous sand burrowers. They all use a very large, broad foot to smother their prey, which in the case of harps are small crabs and shrimps.

Harps have long eyestalks and a long siphon. With a predator in hot pursuit, harpas are also notable for amputating the rear of the foot, leaving a writhing remnant to distract a pursuer. The sharp shell edge is used for amputation. Harps also have a wide spade-shaped expansion on the front portion of their foot, which they use for digging.

Old taxonomic references have sometimes grouped Harpa with Magilus and Coralliophila under the Magilidae family name. The Harpa mollusc is different anatomically and in mode of living.