Caenorhabditis elegans worm, coloured scanning electron micrograph (SEM). C. elegans is a soil-dwelling hermaphrodite nematode worm and one of the most studied animals in biological and genetic research. A tendency to reproduce by self-fertilisation (resulting in identical offspring), along with the short time taken to reach maturity, make this tiny worm an ideal subject. Magnification: 500 when printed at 10 centimetres wide.