Coloured scanning electron micrograph (SEM) of microbes on humus from the Northern Black Forest, Germany. Seen here are budding yeast (orange), bacteria of different species and size (bright green) and the remnants of the shell of a protozoan (orange). Humus is the decomposition product of leaves, wood and other vegetable remains that are decomposed by bacteria, yeasts, fungi and protozoa, as well as mites and small insects. Magnification: x6600 when printed at 15cm wide.