Tentative serial “Sshape” transformation of the T. (Nannomonas) hyperpachymorph to the sphaeromorph (“tent folding” model). Photo by Marc Desquesnes. In this series, the “S” shape of the flagellum seems to fold on itself like a spring (snapshots 1- 6), so the anterior and posterior ends move closer to each other like a collapsible tent (snapshots 7–12). The cytoplasm ends up in a sphere (snapshots 13–18).