Lichens are composite organisms that form when algae or cyanobacteria live in the filaments of fungi in a mutualistic relationship. Lichen, which lack roots, obtain most of their necessary elements from the air; the elemental levels in lichen can reflect the composition of ambient air. As a result, many studies of lichens have emphasized their role as bioindicators of air quality, as well as climate change, pollutants such as phosphate from industrial fertilizers, and heavy metal contamination.[1][2]