Found 30 metres underground at a coal mine, they are dubbed Jurassic pearls or the marbles of a Siberian colossus. The ten spheres are around half the size of a human, a metre or so in diameter, and almost perfectly round and smooth. To add to the mystery, they change color after rain.
They were unearthed by an excavator at Sereulsky coal mine, in the Nazarovo district of Krasnoyarsk region, lying close together.
It was as if they had been carefully buried by a prehistoric giant only to be found many millennia later. Or was there some extra-terrestrial explanation to this geological curiosity now on display at the mine?
The experts have ruled out the more fantastical versions - including theories that they were manmade - and say these stone creations are a leftover from Jurassic times. The strange balls were formed by a natural process likened to the formation of pearls.
