Sandro del Prete

This new shape, though different from the one above it, has the same qualities as the other figures. An object would travel a full cycle along its path in a clockwise direction - and once again in a counterclockwise direction - without passing over the other objects on the ring disk. The object moves toward the observer or in the opposite direction, away from the observer, but this to-and-fro motion illusory. It relies on a temporal element, and could therefore be called four-dimensional.