A lunule (from the Latin meaning small moon or crescent moon) is an anatomical feature which is found in the exterior surface of the shells of some species of clams,

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

s, as for example in the family

Veneridae The Veneridae or venerids, common name: Venus (mythology), Venus clams, are a very large family of minute to large, saltwater clams, marine bivalve molluscs. Over 500 living species of venerid bivalves are known, most of which are edible, and m ...

and in the genus ''

Ascetoaxinus ''Ascetoaxinus'' is a genus of saltwater clams, marine bivalve molluscs in the family (biology), family Thyasiridae. The shells of species in this genus have a Lunule (bivalve), lunule with a scalloped margin. The genus was first described in 20 ...

''. The lunule is a well-defined area near the hinge line of the shell, anterior to the beaks. Website conchs.org, The Conchological Society of Great Britain and Ireland, Molluscs, Glossary, Advanced glossary of molluscan terminology, Lunule, by Steve Wilkinson, 5 November 201

Accessed 2014.12.9 Despite the name, a lunule is not always in the shape of a crescent moon. Details of the lunule are sometimes an important diagnostic feature in identifying a bivalve shell. Chionopsis intapurpurea valve view

References

{{Bivalve anatomy Bivalve anatomy Mollusc shells