Monoplacophora
/ˌmɒnə(ʊ)pləˈkɒf(ə)rə/Zoology
noun
A class of mainly extinct univalved marine molluscs with a limpet-shaped shell, whose surviving members are found in deep water. Also (usually in form monoplacophora): molluscs of this class.
Origin
1950s; earliest use found in Nature: a weekly journal of science. From scientific Latin Monoplacophora, class name from mono- + ancient Greek πλακο-, πλάξ flat plate, tablet + -ϕόρος, after Polyplacophora.