Coloured scanning electron micrograph (SEM) of fungal hyphae (bright) growing through woody debris from the Northern Black forest, Germany. Also seen are bacteria (red), the remains of an amoeba (left, yellow), the shell of a testate amoeba (centre left, blue) and a moss leaf. 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: x500 when printed at 15cm wide.