This is a strangely unique object, the Wobbler:

The Wobbler is made of metal, with a brushed chrome surface, and has an elegant ‘feel’ to it. It also has a strange ‘wobbling’ action if you roll it across a smooth surface. On a slight slope it rolls of its own accord, and almost seems to have internal propulsion. Definitely a very elegant WIF - a What’s It For?

You can see a video of it in action which reveals it’s hidden use.

Available to buy from Grand Illusions for £69.00, ouch!