Coloured scanning electron micrograph (SEM) of fungal hyphae (bright) growing through a piece of woody debris from the Northern Black forest, Germany. Also seen are Streptococcacea (red) and other bacteria (yellow). Fungi are the first organisms to decompose wood because they can split and utilise lignin, a complex compound in the woody cell walls of plants. Together with bacteria and microscopic animals, they form humus from organic waste. Magnification: x200 when printed at 15cm wide.