Nummulites

Nummulites [′nəm·yə‚līts]

(invertebrate zoology)

A genus of unicellular shelled protozoa of the order Foraminiferida (superfamily Nummulitacea, family Nummulitidae). The discoidal, lenticular, or globular test or shell can reach a diameter of about 5 inches (12 centimeters) and is composed of finely perforate calcium carbonate, it consists of planispirally enrolled whorls of many tiny undivided chambers.

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Nummulites 

a genus of extinct unicellular organisms of the subclass Foraminifera. Remains of Nummulites have been found in Upper Cretaceous and in Paleogene deposits in the tropics and subtropics of Europe, Asia, Africa, and America. Nummulites had a lenticular or discoid shell with a diameter that ranged from 1 to 16 cm. The shell contains many whorls divided by septa into chambers; each new whorl completely overlaps the next older whorl. Nummulites led a benthopelagic mode of life. Aggregates of their shells formed nummulitic limestone, which is used as a building material. Nummulites are important index fossils in the stratigraphy of the Paleogene.

REFERENCE

Osnovy paleontologii: obshchaia chast’: prosteishie. Moscow, 1959.