On the tree trunks and various stone formations, you will see lichen, a combination of fungus and algae that work together to maintain a symbiotic relationship called mutualism. The fungi provides protection for the algae which it turn provides food for the fungi. Though lichen are capable of growing in a variety of extreme ecosystems, they are sensitive to any disturbance in their environment. Lichen are capable of shutting down metabolically during unfavorable conditions, forcing growth to slow to less than a millimeter per year. There are three specific types of lichen; foliose, crustose, and fruticose. All three forms of lichen can be found throughout the forest. The lichen shown here is considered foliose, identified by its clover-like edges. Crustose lichens have a crust-like texture and resemble paint splattered on stone. Finally, fruticose lichen is identified as shrub-like, growing outwards with multiple branches.