Gryphaeidae
| Gryphaeidae Temporal range: Middle Triassic to Recent |
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| An intact fossil shell of Exogyra flabellata (Owl Creek Formation, Late Cretaceous, Ripley, Mississippi), held in a human hand | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Bivalvia |
| Order: | Ostreoida |
| Superfamily: | Ostreoidea |
| Family: | Gryphaeidae Vyalov, 1936 |
| Genera | |
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The Gryphaeidae, common name the foam oysters or honeycomb oysters, are a family of marine bivalve mollusks, and are a kind of true oyster. This family of bivalves is very well represented in the fossil record, however the number of living species is very few.
All species have shells cemented to a substrate. Shells are considered brittle, inequivalve, with the left, lower (cemented) valve convex and the right (upper, non-cemented) valve flat or slightly concave.
Genera and species within this family are divided into three subfamilies, Exogyrinae, Gryphaeinae and Pycnodonteinae. Both Exogyrinae and Gryphaeinae are completely extinct. Only four genera Hyotissa, Parahyotissa, Pycnodonte and Neopycnodonte in the subfamily Pycnodonteinae have extant species.
Genera and species within the family Gryphaeidae include: Family Gryphaeidae Vialov, 1936 (some genera also known as Devil's toenails)
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