Brief Description: Genus of rhizopoda protozoa that belongs to the family of nummulites. They are also called nomismatolithi (coin-stones), because they look like coins when they have large dimensions. The members of the family Nummulitidae are plenty and characterize the early tertiary layers of the Mediterranean. They also serve as stratigraphic indicators (from Palaeocene until Holocene). For example, the Egyptian Pyramids were constructed with nummulite limestone of the Eocene period. The shape of the shell is disc-like or lens-like or spherical. It can reach a diameter of 12 cm and consists of calcium carbonate. Their reproductions can be either sexual or genderless. The interchange between these reproduction types in a species leads to consecutive diploid and haploid generations of distinctive difference in size. 
Bibliography: Γεωργιάδου-Δικαιούλια, Ε., Συμεωνίδης, Ν., Θεοδώρου, Γ. (2003) Παλαιο-ντολογία (μέρος Α?), Εκδόσεις Γ. Γκελμπέση, Αθήνα.