Aspergillus niger. Coloured scanning electron micrograph (SEM) of a fruiting body of the fungus A. niger, on the tip of a conidiophore. The small black spheres are spores (reproductive cells), about to be released into the air. In the background are a network of vegetative filaments called hyphae. A. niger grows in household dust, soil, and decaying vegetable matter, including stale food. It is one of the most common causes of otomycosis (fungal ear infections) and, if large amounts of spores are inhaled, may result in the serious lung disease aspergillosis. Magnification: x830 when printed 10 centimetres wide.