Gravel deposit made up of Nummulites striatus fossils from Maians (Castellfollit del Boix) in 1st image, from Colonia Jorba (Calders) in the 2nd image and from Les Marcetes (Manresa) in the 3rd. The biggest pieces measure 25 mm diameter, most of them round 10 mm.
The Nummulites are the most characteristic fossils in the Eocene marine rocks. The name derivates from the latin word for coin, this is nummulus, because their shape like a disk. The Catalan words for Nummulites are llenties (= lentils) or dinerets (= coins). There is plenty of Nummulites in several places in the district of Bages.
The compact limestone of Sant Vicenç that is extracted for ornamental purpose is mainly made of Nummulites. Nummulites were marine protozoa with a calcium carbonate skeleton. They belonged to the group of foraminifera. Their diameter ranged between few millimeters to maximum 6 cm.
The Nummulites characterize the levels of the marine Eocene strata.
[photos Florenci Vallès (1st) and Jordi Badia (2nd and 3rd)]
- See also the article Pedres milionàries, in Catalan, by Jordi Badia.