British soldiers on dead tree

Lichens are a combination of algae and fungi, the classic example of mutualistic symbiosis. The algae can carry on photosynthesis, and make food. The fungus can anchor itself most anywhere. This combination grows on bricks, rocks, roofs, above the tree line, in the Arctic, and in other places where other plants won't grow.

Perhaps, for esthetic reasons, I should have removed the pine needle.

For more on lichens in general, see here. The red-tipped lichen, Cladonia cristatella, is called British soldiers lichen.

The green in the background is mostly moss. See larger sizes for more detail.