A Beach in New Zealand Is Covered With Nearly Perfect Stone Spheres
Huge spherical concretions emerge from coastal cliffs and rest on the beach like stone cannonballs.
The Moeraki Boulders are large, unusually round concretions exposed by erosion along Koekohe Beach in New Zealand.
They formed as minerals accumulated around a core within ancient seafloor sediment, gradually cementing the surrounding material.
As cliffs erode, the boulders are released onto the beach, where their geometry makes them look almost manufactured.
Photo: Pavel Špindler · CC BY 3.0