Lichens are formed from more than one organism, and they are important

lichens, Blowing Rock, North Carolina, USA

Lichens are inconspicuous entities, usually. They don't stand up high. Most of them aren't colorful. They are interesting, and important.

One interesting aspect of lichens is that they are made up of two or more types of organism, I was taught, and taught, that these were a fungus and an alga. The fungus provided structure and protection for the alga, and the alga provided food, from photosynthesis. That's true, but not true of all lichens. Some of them are a combination of an alga, and a yeast and/or a bacterium. 

Since they are more than one type, they can't reproduce as most organisms do -- by producing a copy of themselves. Lichens increase in numbers when a piece of a lichen breaks off.

Lichens are able to grow where other organisms, or groups of organisms, can't. They are capable of growing on bare rock or concrete, perhaps even on metal. For more about that, see here.

Although lichens are small, there are so many of them in some Arctic regions that they furnish much of the food for reindeer populations.

Thanks for reading!