Scientists at Tel Aviv University found the cone-shaped monument, approximately 230 feet in diameter, 39 feet high and weighing an estimated 60,000 tons, while conducting a geophysical survey in the southern Sea of Galilee, a university release said Monday.
The site resembles early burial sites in Europe and was likely built in the early Bronze Age, Yitzhak Paz of the Israeli Antiquities Authority said.
Due to a natural build-up of sand throughout the years, the base of the monument is now six to ten feet below the bottom of the Sea of Galilee, the researchers said.
"The base of the structure -- which was once on dry land -- is lower than any water level that we know of in the ancient Sea of Galilee," Shmulik Marco of Tel Aviv University said.
The structure was not a random accumulation of stones but a purposefully-built structure composed of three-foot-long volcanic stones called basalt, he said, and the stones were probably brought from more than a mile away and arranged according to a specific construction plan.
A future hunt for artifacts will help to more accurately date the monument and could give clues as to its purpose and builders, the researchers said.