Thank you! I didn´t know this either... I always thought they are some kind of parasites engulfing the trees. Then a couple of years back, I was fascinated by lichens I found spreading on a tree. Rounder bigger organisms of various vivid colors of yellow, green and bluish shades. I thought of researching and found out that they are good to the ecology. Since I love nature, I decided to post this info in this community so everyone who ever reads would know that these organisms are good to our environment.