What is a lichen?

Answer 1

A lichen is a symbiotic organism that is composed of a fungus and a photosynthetic partner, usually either algae or cyanobacteria. The fungus provides a structure and protection for the photosynthetic partner, while the photosynthetic partner provides food through photosynthesis. Lichens can come in a variety of forms, including crust-like, leafy, or branching structures, and can be found growing on rocks, trees, and soil in many different environments.