The rock in the village of Kalaʻau in Tongatapu which has a mythical link to demigod Maui has a scientific theory.
Tongan legend said Maui, who lived in the island of ‘Eua, was angered by the noises made by his father’s rooster when it crowed in the morning.
He then hurled the huge stone at it and it killed the bird before the rock landed at the Hihifo village, about 50 kilometres away from the island.
But a team of Japanese researchers theorised the large coral boulder was brought inland from the ocean by a massive tsunami that struck Tonga thousands of years ago.
The connection between the hypothesis and the historical site was significant to the Japanese as they were pushing for the United Nations General Assembly to adopt November 5, as World Tsunami Awareness Day.
Known as Maka Tolo ʻA Maui or Mauiʻs throwing rock the government officially recognised it in a plaque unveiling ceremony on Tuesday.
The ceremony coincided with the arrival of a parliamentary delegation from Japan led by the Secretary-General of the Liberal Democratic Party of Japan Mr Toshihiro Nikai.
They were invited and they joined Tonga’s Deputy Prime Minister and guests at the historical event.