This family of bivalves is very well represented in the fossil record, however the number of living species is very few.

Shells are considered brittle, inequivalve, with the left, lower (cemented) valve convex and the right (upper, non-cemented) valve flat or slightly concave.

[2] Genera and species within this family are divided into three subfamilies, Exogyrinae, Gryphaeinae and Pycnodonteinae.

Only two genera Hyotissa and Neopycnodonte in the subfamily Pycnodonteinae have extant species.

[3][4][5] Genera and species within the family Gryphaeidae include: Family Gryphaeidae Vialov, 1936 (some genera also known as Devil's toenails)