Definition: Organism generally recognized as a single organism that consists of a fungus and an alga or cyanobacterium living in symbiotic association. Often attached to solid objects such as rocks or living or dead wood rather than soil.
Definition: Museum National d'Histoire Naturelle (MNHN), Paris, France. URL for main institutional website: http://www.mnhn.fr/museum/foffice/science/science/sommaire.xsp
