Lichen

Habitat:

Spotted on a stone. Hill.

Notes:

Lichen is a composite organism that arises from algae or cyanobacteria (or both) living among filaments of a fungus in a symbiotic relationship. Lichens may be long-lived, with some considered to be among the oldest living things. Many lichens are very sensitive to environmental disturbances and can be used in cheaply assessing air pollution, ozone depletion, and metal contamination. Lichens have been used in making dyes, perfumes, and in traditional medicines. Few lichen species are eaten by insects or larger animals, such as reindeer.