Survivors!

Lichens consist of symbiotic relationship between an alga and a fungus. Algae, fungi and lichens will grow in the most inhospitable of places.  In the photograph a yellow lichen is growing on the roof tiles of these town houses and a red alga is flourishing on the stucco walls.

As Steven L. Stephenson  notes in his book The Kingdom Fungi: The Biology of Mushrooms, Molds, and Lichens,   "One could speculate that lichens will be among the last inhabitants to succumb on a dying earth at some distant point in the future.”