C. elegans nematode worm. Light microscopy footage of a specimen of the nematode roundworm Caenorhabditis elegans. Nematodes are small worms found in a range of environments worldwide. C. elegans is a transparent, soil-dwelling nematode, found in temperate climates. It feeds on bacteria, and reaches lengths of about 1 millimetre. C. elegans is used extensively in biological research. In this footage, the head end moves forward, probing its environment, before being withdrawn as it retreats.