Like stepping stones leading from a bygone era into this one, the enduring spheres in “Boulders on the Beach” resolutely withstand turbulent skies and rippling sea currents. Originally formed on the ocean floor 65 million years ago, New Zealand’s Moeraki Boulders weigh several tons and have an average diameter of 9 feet. The boulders were gradually exposed through erosion, and have become one of New Zealand’s major tourist attractions. According to Maori folklore, the mysterious boulders arose from gourds and calabashes that washed ashore when a legendary canoe wrecked 1,000 years ago.