Oops. It looks like the last 2 posts got flip-flopped. Sorry about that. This is just a little FYI. In Gregory's Junior Pioneer Book from the Oregon Trail Interpretive Center they provided information regarding the difference between lichen and moss. So, when I saw the below rock with both I thought I'd pass the information along. We've seen a lot of both on rocks, trees and fence posts, etc.
Lichen: A plant-like growth that is actually a result of a fungus and algae living together. It grows very slowly, lives for a long time, looks like moss or a crusty dry leaf and can grow on bare rock or soil.
Moss: Small green plants that have hairlike structures called rhizoids instead of leaves, stems, and roots. These rhizoids grow into the soil and help the plants get water and minerals.