Decomposers are organisms that break down dead or decaying organisms and thus they carry out the natural process of decomposition. In this case examples are; Fungi in association with a fallen log, A fungi association with a dead rabbit, Coprophilous fungi.
Mutualist is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other. In this case examples are; Mycorrhizal fungi on tree roots, fungi in the family Lepiotaceae.
Parasitism is a relationship between species , where organism, the parasite, lives on or in another organism, the host causing it some harm, and is adapted structurally to this way of life. Examples in this case includes; Trichophyton spp, Cryphonectria parasitica, Cordyceps spp, Septobasidiu spp. and an individual scale insect infeted by fungal hyphae.