it’s lichen! Together, some fungus and algae create an organism called lichen. In a symbiotic relationship, the algae and fungus both help each other survive. … be careful not to touch Lichens because they are fragile.

Is lichen harmful to humans?

Lichens Historically Used as Food A few species have been eaten by humans, however. Many species are believed to be mildly toxic, at least a few are poisonous, and most are indigestible in their raw form.

Is lichen dust harmful?

To reiterate: the lichen is in no way harming your tree, but the presence of lichen may point to an unhealthy or dying tree (caused by other reasons, such as pests or disease).