Lichens are composite entities, consisting of a fungus (called the mycobiont) and a green algae or cyanobacterium (called the photobiont). Sometimes there are a lot of bacteria involved too. The photobiont lives entirely within the tissues of the mycobiont, sort of like putting the garden patch inside your spleen. And you name them after the fungus.
It is almost impossible to identify many lichens. Some are only properly identified with a series of chemical tests and a very good microscope. Which is a pity because they can tell you about air quality, water quality, radiation content, heavy metals, basically a buncha nasty stuff. Also it is more polite to know their names. But what can you do?
Some lichens can fix nitrogen, just like peas, but they do this slowly and are not good with rosemary and butter so are not a good substitute for peas.
If you separate the photobiont and the mycobiont in a lab, you cannot usually get them back together. Lichens do not live in the past.
Lichens have successfully survived A YEAR AND A HALF OUTSIDE IN OPEN SPACE. So don’t be snotty about having a big brain and fingers and stuff. They may have survived longer, but someone had to take the box back inside.
Some lichens glow under a UV light. This is really really cool and will cause you to go hide in the closet with twigs. And these aren’t the space lichens either. They’re just normal lichens. Bioluminescence is not particularly rare either.