In general, fungi have a very short life span, though it differs greatly from species to species. Some types may live as short as a day, while others survive anywhere between a week and a month. The life cycle of a fungus begins as a spore and lasts until germination.
Fungi begin their life as spores that are released from a fully grown fungi. After they are released, the cells of the spore divide and spread into hyphae. When hyphae formed from spores released by two different fungi meet, they may fuse together to create a single cell with two nuclei.
Once the two-nucleus cells, also called dikaryons, have matured, they develop into a fruiting body known as a mushroom. The nuclei of the cells in the mushroom will undergo further divisions and eventually form haploid cells--cells with a single set of chromosomes--that then divide through meiosis and create spores.
Once a fungus has completed creating spores through meiosis, it effectively dies. The spores spread and the remaining stalk and hyphae do not got through another fruiting process. The remnants of the fungus then decompose in the soil.