Organisms help in soil formation by taking part in the process of weathering. Lichens and bryophytes are involved in biological weathering. Lichens grow on the surface of rocks, creating small cervices by extracting minerals from them. Soil builds up in the thin layer of cervices. Mosses grow on these cervices and deepen the cervices, thereby building up more soil inside them. Cervices get more deepened and form cracks, which become wider and deeper when the roots of the herbs enter them.