Primarily survive on non-living organic material, are called SAPROPHYTES
The non-reproductive "body" of most fungi (called the vegetative phase) is composed of a mass of a fungal threads called HYPHAE (singular = HYPHA )
This mass of hyphae is called a MYCELIUM (plural = MYCELIA ). While an individual hypha is microscopic, mycelia are often visible with the naked eye.
HYPHAE (singular = HYPHA ) are the threadlike structures that comprise the major body of a fungus. You can think of a hypha as a long tube. Many hyphae in a mass are called MYCELIUM (plural = MYCELIA ).