What helps lichens to effectively overcome adverse living conditions?

Lichens are special living organisms that consist of a symbiosis of fungi and blue or blue-green algae. In this symbiosis, algae receive water and mineral salts from fungi, and fungi receive organic substances from algae, which they produce in the process of photosynthesis. That is, the lichen is a closed system capable of self-sufficiency. This allows lichens to survive in adverse conditions and on impoverished soils. Indeed, the main habitat of lichens is mountain slopes and concrete structures.