45.3458°N, 170.8260°E.
Concretions on Koekohe Beach on the Otago coast of New Zealand's South Island. Approximately 50 spherical and ovoid boulders ranging from 0.5 to 2.2 metres in diameter, with masses up to several tonnes. Composed of mudstone cemented by calcite and dolomite, they formed approximately 60 million years ago in seafloor sediments by chemical concretion around small organic nuclei (often a fossil) — accreting layer by layer over an estimated 4 million years. Eroded out of the cliff face by wave action over the last several thousand years. Internal cracks have radiated from the centers of larger boulders as they continue to dehydrate and contract. Maori oral tradition identifies the boulders as eel baskets and food calabashes from the wreck of the canoe Arai-te-uru.
Sixty-million-year-old spheres rolling out of a cliff one at a time as the cliff erodes — each one took four million years to form on the bottom of an ancient ocean.