Aspergillus is a type of fungus which causes aspergillosis. It is commonly found growing on dead leaves, stored grain, compost piles or in other decaying vegetation. It can grow on marijuana. Most people come into contact frequently with aspergillus, but are rarely infected if they have a normal immune system. Apergillosis can also occur as an allergic response, usually caused by Aspergillus fumigatus.
Attribution: Avallain