The Mysterious Moeraki Boulders

Planet Earth

If you go down to Koekohe beach in New Zealand you can be sure of a big surprise. In front of you, scattered like enormous marbles from some long abandoned game between giants, are hundreds of spherical rocks. Or are they the egg shells of sea-born dragons?

The Moeraki boulders present us with a mystery - what are they and how on earth did they get here?