nummulite

Fossil nummulitid foraminiferans showing microspheric and megalospheric individuals; Eocene of the United Arab Emirates; scale in mm.

Fossil Nummulites in Urbasa, Basque Country

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 reach 6 cm (2.4 inches) in diameter, and are common in Tertiary marine rocks, particularly around the Mediterranean (e.g. Eocene limestones from Egypt). Fossils up to 6 inches wide are found in the Middle Eocene rocks of Turkey.² They are valuable as index fossils.

The name "Nummulites" is a diminutive form of the Latin nummulus meaning "little coin", a reference to their shape. In 1913, Randolph Kirkpatrick published a book, The Nummulosphere: an account of the Organic Origin of so-called Igneous Rocks and Abyssal Red Clays, proposing the theory that all rocks have been constructed by the accumulation of forams such as Nummulites.

References

• 'Nummulite', Tiscali Dictionary of Animals [1], retrieved 17 August 2004
• 2. 'Biggest Microbes', Guinness World Records 2001, p. 153.

• http://paleopolis.rediris.es/cg/CG2006_M02/index.html