Lichens are called pioneer colonisers of bare rock. How can they help in the formation of soil?

(N/A) Lichens are the first organisms to colonize bare rocks,which is why they are called pioneer species.
They secrete organic acids (such as oxalic acid) that chemically weather the rock surface.
This process breaks down the rock into smaller mineral particles.
Over time,the accumulation of these mineral particles,along with the dead organic matter from the lichens themselves,contributes to the formation of a thin layer of soil,which allows other plants like mosses to grow.