On the Masse Mystérieuse watch, the hands float in the case. The entire 9801 MC movement, which took 8 years to develop, seems weightless. All components that receive energy from the movement, transmission and regulation are integrated in the rotor. The rotor itself is skeletonised to make this moving spectacle visible. In the centre, an ultra-sophisticated differential system has been integrated into the movement to prevent the time display from being caught in the mass.