Author Jean-Marc Di Meglio discusses the science behind the featured cover of the June 20 issue of Biophysical Journal. The figure is from the article, Locomotion control of Caenorhabditis elegans through confinement, by authors Félix Lebois, Pascal Sauvage, Charlotte Py, Olivier Cardoso, Benoît Ladoux, Pascal Hersen, Jean-Marc Di Meglio I became interested in the study of the C elegans worm a few years ago, looking originally for a biological model to investigate the relation between the sense of touch and the physics of contact. As for most physicists, geometrical shapes - and their formation - are very important in my approach of research and I still remember how, looking at worms through a microscope for the first time, I was immediately fascinated by the sine shape of crawling worms: there are very few realizations of sinusoidal shapes in nature while the sine representation is ubiquitous in physics. We then started to work on the locomotion of C. elegans and its dependence on its mechanical environment. The figure of the cover, prepared by Pascal Hersen and Félix Lebois, represents, along with a nice microphotograph of the worm, the shapes of the worm when it crawls on a gel, when it swims in a liquid or when it continuously adapt its locomotion to its confinement. The latter superimposition of shapes reveals that the worm has in fact a single gait which can be modulated by its mechanical environment. I was struck by the uncluttered and sleek character ot these motion decompositions, reminiscent to me of the chronophotographs and their subsequent analysis of Étienne-Jules Marey, a precursor - with Eadweard Muybridge - of locomotion analysis.