Look at just about any cliff or boulder around the American Southwest, and you’ll probably see at least one variety of lichen clinging to the surface.

This stuff comes in an array of colors, textures and architectures — orange, green, teal, leafy, crusty — and is the result of multiple kingdoms of life entering into symbiotic relation. (Moss falls squarely into the plant kingdom, and so is considered very different than lichen — even though moss often grows on rock outcroppings as well.)

Sometimes lichen is part algae and part fungus. Other times it’s part fungus and part bacteria. Biologists identify around 20,000 different kinds worldwide.

Learn More:

• Lichen (Wikipedia)
• The Lichen Photo Gallery (University Of Oslo)

(Today’s photo of lichen on billion-year-old Sandia granite is courtesy of Natalie Rae Good’s Tumblr.)