The famous Moeraki boulders lie scattered along a beach 40 kilometres south of Oamaru, New Zealand.
According to Maori legend, the boulders are gourds washed from the great voyaging canoe Araiteuru when it was wrecked upon landfall in New Zealand some 1000 years ago.
Scientists explain the boulders as septarian concretions formed about 65 million years ago. Crystallization of calcium and carbonates around charged particles in muddy undersea sediments gradually formed the boulders in a process taking as long as four million years. The soft mudstone containing the boulders was raised from the seabed around 15 million years ago and sea erosion is exposing the erosion-resistant boulders.