MEXICO CITY -- Mexico announced Friday that a huge 2,500-year-old Olmec stone sculpture has been returned from the United States.

The almost six-foot-tall (two-meter) “Monster of the Earth” sculpture appears to represent the gaping maw of a monster that is big enough to swallow people, and may represent a symbolic entrance to the underworld.

Experts say the sculpture is important because of the insights it provides on the cosmological vision of the Olmecs, considered a founding culture of Meso-America.

Foreign Relations Secretary Marcelo Ebrard said the sculpture was handed over at the Mexican consulate in Denver, Colorado, on Friday.

Experts believe the sculpture was taken clandestinely in the 1960s from Chalcatzingo, a lesser-known ruin site south of Mexico City.

“It was like an open wound, not having this artifact,” Ebrard said.