Bacteria and cars actually seem to have something in common: they use a pretty similar mechanism to disconnect the engine from the wheels. When pushing the clutch pedal of a car, the driver prevents the engine from turning the wheels. Comparably, bacteria seem to have a "protein-clutch" that prevents the bacteria's hydrogen-driven motor-protein to turn its propeller, the so called "flagellum". Isn't it amazing, that engineers came up with a quite similar idea like evolution?