Moss, one of my favourite plants..

On the roofs above our heads, on garden walls, and in cracks in the pavement; mosses are growing all around us. 

Mosses are an environmentally benign way to conserve water, control erosion, filter rainwater, clean up hazardous chemicals, and sequester carbon. Also, mosses serve a valuable ecological role as bioindicators for air pollution, acid rain, water pollution, and wastewater treatment.

Often overlooked, these tiny plants have incredible properties. From hot deserts to damp caves, they can survive in extreme conditions and play an important role in biodiverse habitats across the world. 

https://www.kew.org/read-and-watch/moss