Question

What are lichens?

Answer 1

Lichens are composite organisms made of a fungal partner living in close symbiosis with a photosynthetic partner (a green alga and/or a cyanobacterium), the fungus provides structure and protection while the photosynthetic partner produces food by photosynthesis; lichens can colonize bare surfaces (rock, bark, soil), absorb nutrients from the air, and even secrete acids that slowly break down rock and help form soil.