I Like Lichen

Lichens are organisms consisting of a fungus and a green or blue-green alga growing together in a mutually beneficial, symbiotic, relationship.  The entire structure is called a thallus. The fungus obtains water and minerals from the air and the material it is growing on.  The alga provides carbohydrates and vitamins. Grow in the tree canopy but falls to the forest floor, where it is consumed by deer, elk, and other animals. Fixes nitrogen from the air, which then enters the local ecosystem when eaten or when absorbed by rootlets which the host trees extend from their own bark into the lichen.