Wall screw moss forms bright green cushions up to 5 centimetres across and 2 centimetres high. It has tiny leaves that end in a small white hair. Unlike other mosses, it has no true roots. The moss reproduces by scattering dust-like spores from slender, cylindrical spore capsules carried vertically on comparatively long stems. The spore capsules have pointed hoods initially, which fall to release the ripe spores.
This extremely common moss grows on rocks and walls throughout Europe. Like all mosses, it needs humidity in order to reproduce and therefore flourishes in damp places.