Lichen is an example of

Lichen is an example of a symbiotic association between a fungus and an alga or a cyanobacterium. The fungus provides a structure for the partnership, while the alga or cyanobacterium provides the food through photosynthesis. The partnership is so close that lichen is often described as a single organism, even though it is made up of two different types of organisms. Lichens can be found in a variety of environments, from the arctic tundra to the rainforest, and are important as indicators of air quality and ecosystem health.