- Lichens are a symbiotic relationship between a fungus and an algae or cyanobacteria, where the algae or cyanobacteria lives within the fungus. The algae photosynthesizes to provide food for both organisms while the fungus provides protection and absorbs water and minerals. - Lichens can reproduce sexually through spores or asexually through soredia or isidia. They grow in harsh environments where few other organisms can survive and are sensitive to air pollution. - Lichens come in many forms from crustose to foliose to fruticose and are identified by features like their body type, life form, lobes, surfaces, and reproductive structures. They indicate air quality