Have you ever noticed how the surface of an old log or boulder can be painted with a multitude of different colored organisms? Lichens are among the most common and most overlooked organisms in Rocky Mountain National Park. They grow on rock surfaces, trees, and downed logs, and on the ground; Some even grow free of substrate and blow around like miniature tumbleweeds. Lichens are actually a partnership composed of two organisms - a fungus and a primitive plant called an alga. Fungi (pleural of fungus) are colorless organisms that generally make their living decomposing other organisms, while algae (plural of alga) can make their own food by photosynthesis. In the composite association we call lichens, the fungi provide the protection from the environment, while the algae provide the food. This kind of arrangement where both organisms benefit from their association is called a symbiotic relationship.