This is a kinetic femisphere. It rolls "spontaneously" by a 'mechanism' small enough to be hidden within. Internal batteries, microcontroller and motor shift the femisphere's balance from time to time. The microcontroller chip is programmed to produce a wide variety of movements on a computer, then moved into the piece. It is difficult from the static photo to get any feel for the aesthetiques of the movement that the object creates in real life. You can see a brief video of this on YouTube, search under "niagaraturner". For my tastes the movements here are at random intervals, with random 'vigor', and from random positions, keeping the movement relatively calm but unpredictable/interesting; this piece carves out a significant 'presence' in time!