A cauldron-shaped sundial made during the Joseon Dynasty has returned home from the United States.

The Cultural Heritage Administration said on Tuesday that one of the country's Angbuilgu public clocks was returned to South Korea in August, after the Overseas Korean Cultural Heritage Foundation bought it at a U.S. auction in June.

Officials say, however, that it's unknown when and how the clock was taken overseas.

The Angbuilgu was invented during the reign of King Sejong in the 15th century to tell the 24 solar seasonal terms, as well as the hours of the day, using lines and curves to indicate the time with a long thin rod in the middle.

Measuring 24-point-one centimeters in diameter and eleven-point-seven centimeters high, the copper alloy sundial, featuring a refined silver inlay and dragon- and turtle-shaped legs, is presumed to have been made between the 18th and early 19th century.

There are seven Angbuilgu sundials in South Korea, while three others are known to be overseas - two in Japan and one in Britain.

The latest Angbuilgu sundial will be displayed to the public until December 20 at the National Palace Museum of Korea.