This round rock could be the oldest stone sphere made by human hands, says Bosnian archaeologist Semir Osmanagic.

Discovered in a forest near the Bosnian town Zavidovici, the ball has a radius of between four and five feet, and an "extremely high" iron content.

Dr Osmanagic believes the sphere proves the existence of an advanced lost civilisation dating back more than 1,500 years ago.