The Moeraki Boulders are located near Moeraki, a small town south of Hampden on the Otago Coast (north of
Dunedin). It includes a number of big spherical stones on the beach near Moeraki. These boulders are grey round blocks and are classed as being septarian concretions; they have been formed by a process
similar to the formation of oyster pearls, whereby layers of material cover a central nucleus or core. For the oyster, this core is an irritating grain of sand. For the boulders, it was a fossil shell, bone fragments or even just a piece of wood. Lime minerals in the sea accumulated on the core over time, and the concretion grew into perfectly spherical shapes up to three meters in diameter. They were originally formed by ancient seafloor sediments during the early Paleocene around 60 million years ago. According to Maori legend the boulders are remains of calabashes, kumaras and eel baskets that washed ashore after the legendary canoe, the
Araiteuru was wrecked at nearby
Shag Point (Matakaea).