Mutualism is a symbiotic relationship between individuals belonging to different species. In this type of relationship, both individuals benefit from the association. For example, the lichens growing on the tree pictured here are examples of mutualism. The lichen, pictured here as the green splotches of growth on the tree, are associations of millions of green algae or cyanobacteria held together in a mass of fungal hyphae. Each partner provides something the other could not obtain, both benefiting from their union. The fungus receives food from the alga and in return, provides the alga with a suitable habitat.