Microorganisms that belong to the fungi. The fungus body is usually composed of threads (hyphae, singular; hypha). These hyphae frequently branch in a more or less complex manner forming networks or webs, collectively called “micelium”. Hyphae may be one-celled or composed of many cells placed end to end. Fruiting bodies that grow from hyphae produce spores. Molds are much lest heat resistant than bacteria.