Lichens are the Hardiest of Earth's Inhabitants.

"One could speculate that lichens would be among the last inhabitants to succumb on a dying earth at some distant point in the future."

Steven L. Stephenson,
"The Kingdom Fungi: The Biology of Mushrooms, Molds and Lichens."

Photo: Yellow Lichen on a rock, The Loch, and Taylor Peak, Rocky Mountain National Park, CO, March 2, 2015