Lichen

A lichen is a complex symbiotic organism comprising algae or cyanobacteria living among fungal filaments, with yeasts often present in the outer layer. This mutualistic relationship creates a unique lifeform with properties distinct from its individual components. Lichens play crucial roles in ecosystems, contributing to nutrient cycling and serving as food sources for various animals. They exhibit diverse morphologies, including branched (fruticose), leaf-like (foliose), crust-like (crustose), powdery (leprose), and other forms. Despite their plant-like appearance, lichens are not plants and come in a wide array of colors and sizes. Their ability to thrive in extreme environments and their sensitivity to air pollution make them valuable bioindicators in ecological studies.