Lichens are unique organisms formed by a symbiotic relationship between fungi and algae or cyanobacteria. This partnership allows lichens to thrive in various environments, including rocky surfaces, tree bark, and even arctic tundras. They can absorb moisture and nutrients from the air, making them resilient in harsh conditions. Lichens come in various shapes and colors, often appearing as crusty patches, leafy structures, or branching forms. They play a crucial role in ecosystems by contributing to soil formation, providing habitat for small organisms, and serving as indicators of environmental health, particularly in relation to air quality.