Bio-colonization of stone and masonry is the transformation of a stone or masonry substrate to a one which supports plant or fungal growth.
As historic masonry surfaces and facades begin to deteriorate they become more porous and the texture profile increases which allows fungus or plant life to take root.
As plant and fungus life take root and begin to grow on masonry facades, the deterioration increases at an increasing rate so the more plants take root, the more deterioration happens, even faster.
The pictures below show a brick masonry wall, built with kiln fired historic common bricks. This building is about 122 years old.