Aspergillus fungus. Coloured scanning electron micrograph (SEM) of the fruiting body (round, top) of a typical mould (Aspergillus sp.). A mould is a fungus with a body composed of thin, string-like hyphae (lower centre). Various species of Aspergillus are used commercially, for example in the production of citric acid, or for digesting the starch in rice as a step in making sake (rice wine). Some species of Aspergillus occasionally act as human pathogens. Magnification: x800 when printed 10 centimetres wide.