Lichen consists of fungus and algae. It is based on intertwining hyphae (threads) of the fungus. The mushroom itself, unable to synthesize organic matter, feeds on the products of algae photosynthesis. The fungal hyphae supply water and mineral salts, and photosynthesis occurs in the cells of the algae, therefore the algae supplies the fungus with organic matter. Autotrophic nutrition.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.