The "Snail Ball" rolls s--l--o--w--l--y downhill

YouTube link.

From Grand Illusions, via Nothing to do with Arbroath.  The physics behind this phenomenon is explained in an article (pdf) at Mathematics Magazine, and nonmathematically summarized below this fold...


"...inside the ball, which is actually hollow, there is a viscous liquid and a smaller ball which is very heavy. When the Snail Ball rolls slowly down an incline, it is the smaller, heavier ball inside that determines the pace, and this is slow because of the viscous liquid..."