Lirae (singular lira) are fine lines or ridges (much finer than ribs) that are a
sculptural feature of the outside of the shells of various animals. The term is commonly applied to the
shells of
mollusc
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
s such as
gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s,
bivalve
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
s and
nautiloids. It can also be used to describe similar sculpture on the surface of the shells of
brachiopods.
In addition the word is used to describe fine linear elevations of shelly material within the outer lip of the
aperture of some
gastropod shells.
The adjectival form of the word is "lirate".
References
Mollusc shells
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