What is "nummulite"

Nummulite \Num"mu*lite\, n. [L. nummus a coin + -lite: cf. F. nummulite.] (Paleon.) A fossil of the genus Nummulites and allied genera.

n. A protozoan from the Tertiary period, known only as fossils

n. large fossil protozoan of the Tertiary period

thumb|left|250px|Fossil nummulites in Urbasa, Navarre A nummulite is a large lenticular fossil, characterized by its numerous coils, subdivided by septa into chambers. They are the shells of the fossil and present-day marine protozoan Nummulites, a type of foraminiferan. Nummulites commonly vary in diameter from 1.3 cm (0.5 inches) to 5 cm (2 inches) and are common in Eocene to Miocene marine rocks, particularly around southwest Asia and the Mediterranean (e.g. Eocene limestones from Egypt). Fossils up to 6 inches wide are found in the Middle Eocene rocks of Turkey. They are valuable as index fossils. The ancient Egyptians used nummulite shells as coins and the pyramids were constructed using limestone that contained nummulites. It is not surprising then that the name "Nummulites" is a diminutive form of the Latin nummulus meaning "little coin", a reference to their shape.

In 1913, naturalist Randolph Kirkpatrick published a book, The Nummulosphere: an account of the Organic Origin of so-called Igneous Rocks and Abyssal Red Clays, proposing the unconventional theory that all rocks had been produced through the accumulation of forams such as Nummulites.