Fungi live as either single-celled organisms or multicellular organisms. Single-celled fungi are referred to as yeasts. The vast majority of fungi are multicellular. Most of the body of a fungi is made from a network of long, thin filaments called 'hyphae
All fungi are heterotrophic, which means that they get the energy they need to live from other organisms. Like animals, fungi extract the energy stored in the bonds of organic compounds such as sugar and protein from living or dead organisms.