Leptochitonidae is a of

polyplacophoran Chitons () are marine (ocean), marine molluscs of varying size in the class (biology), class Polyplacophora (), formerly known as Amphineura. About 940 Extant taxon, extant and 430 fossil species are recognized. They are also sometimes known ...

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 ...

. While the subfamily Leptochitoninae has both

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

and

extinct species This page features lists of extinct species, organisms that have become extinct, either in the wild or completely disappeared from Earth. In actual theoretical practice, a species not definitely located in the wild in the last fifty years of cur ...

, all members of Helminthochitoninae are extinct.

References

Chitons {{paleo-mollusc-stub