Why can lichens live in the most barren places?

Lichen is a separate group of living organisms formed by the symbiosis of fungi and algae. The densely overgrown fungal hyphae harbor green or blue-green algae. Mushrooms pull up water and minerals, and algae, capable of the process of photosynthesis, produce organic substances and give them to the fungi. Thus, lichens are closed systems that can exist on infertile soils, rocky slopes, deserts, that is, where neither fungi nor algae could live separately.