Marie-Anne Félix, Ecole Normale Supérieure
The nematode worm Caenorhabditis elegans. Three life stages of C. elegans are shown: an adult hermaphrodite, a smaller larva, and eleven newly laid eggs (with embryos developing inside them). These are all on a lawn of Escherichia coli bacteria (being eaten by the worms as food). The fully-grown adult is roughly 1 millimeter long.