(Palaeontology)the flat disc-shaped calcareous shell of a foraminiferan, found commonly as a fossil up to 8 cm across in marine Tertiary deposits (古生物)钱币虫
Family Nummulitidae, order Foraminiferida: several genera, including Nummulites 钱币虫科,有孔虫目:数属,包括钱币虫属
语源
early 19th cent.: from Latin nummulus (diminutive of nummus 'coin') + -ite