''Pseudoperna'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

very small

oyster Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species, the valves are highly calcified, and many are somewhat irregular in shape. Many, but no ...

s. ''Pseudoperna'' lived in tight groups. This small oyster is commonly found attached in groups to the shell of large species such as ''

Inoceramus ''Inoceramus'' (Greek: translation "fibrous shell" for the fibrous structure of the mineral crystals in the shell) is an extinct genus of fossil marine pteriomorphian bivalves that superficially resembled the related winged pearly oysters of th ...

''. '' Pycnodonte'' and ''Pseudoperna'' are preserved mostly as calcitic valves and are also found attached to '' Mytiloides''.

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Further reading