Lichens are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. There are three main types of lichens: foliose, fruticose, and crustose. Foliose lichens are a horizontally growing leafy type of lichen that is always attached to the surface where it is growing. A fruticose lichen is characterized by a coral -like shrubby or bushy growth structure, with upright (pendulous) branches. A crustoselichen is more like a flat crust on a surface or beneath the rock surface or trees.