Just a stone’s throw from the ocean, indeed.

Small family farms dot the southern coast of Tongatapu, the largest island of Tonga in the South Pacific. But something lies amid the cassava and banana plants that doesn’t belong: a staggeringly large, off-white boulder.

The rock, which features prominently in Tongan mythology, was recently scrutinized by scientists. New results suggest that the object was transported inland thousands of years ago when tsunami waves breached a 120-foot cliff. That event might have been set in motion by an earthquake in the nearby Tonga-Kermadec Trench, the team reported last month in the journal Marine Geology.

Seemingly out-of-place boulders are found in coastal regions around the world. From Japan to the Bahamas, scientists have spotted hulking rocks that simply don’t seem to fit their surroundings. Researchers generally believe that such boulders were transported by moving water, and the powerful waves of tsunamis are often invoked as culprits.

Last July, researchers traveled to Tongatapu to analyze several coastal boulders. On the last day of their planned fieldwork, the team received an unexpected tip from a group of Tongan farmers: A boulder, far larger than the ones the researchers were studying, lay nearby on farmland belonging to the Teisina family.

That boulder turned out to be a behemoth — roughly the size of a two-story house. “It was unreal,” said Martin Köhler, a geoscientist at the University of Queensland in Australia, who led the research. The rock, made of limestone, was also nearly completely camouflaged by vegetation.

“It looked like a hill,” said Mafoa Penisoni, a seismologist at Tonga Geological Services in Nuku’alofa, the country’s capital, who accompanied the researchers.