LICHENS---and a little moss.

Lichen, a.k.a. Reindeer Moss, is a combination of two life forms living mutualistically in benefit to each other. One form is a fungus; the other an alga (singular of algae).

The combination of the two allows lichens to colonize areas that nothing else can use for a substrate....like rock surfaces. The fungus has the ability to grow "holdfasts" into solid rock to anchor itself and acquire minerals. It can also absorb and store water. But it has no ability to feed itself. The alga can feed itself through photosynthesis but it lacks a supply of water and minerals for growth. By living inside the fungal body, the alga has access to water, sun, air and minerals. It photosynthesizes and shares some of the excess sugar produced with the fungus. Thusly, they help each other to survive...neither of which could survive on its own without the help of the other.

They are found in 4 basic forms: Crustose (crust-like growing tight to the substrate surface); Squamulose (tightly clustered and flattened like pebbles); Foliose (leaf-like with flat sheets of tissue not tightly bound; Fruticose (free-standing branching tubes).

I wonder if you can identify which form the bulk of these lichens are?

Best seen clearly in Large.