Otsu, Shiga Pref. ¨C The Shiga prefectural government has announced the discovery of a nearly complete piece of earthenware likely dating back more than 10,000 years at the bottom of Lake Biwa in western Japan.

Estimated to be from the early Jomon period, around 11,000 to 10,500 years ago, the artifact is believed to be the oldest pottery ever discovered at the Tsuzuraozaki underwater archaeological site in Japan¡¯s largest lake.

In October, the prefectural government conducted a survey at the bottom of the lake, where the underwater ruins are located, as part of a project commissioned by the Cultural Affairs Agency.

An unmanned underwater vehicle equipped with four cameras took photos and videos at a depth of some 64 meters.

The Shiga government created a 3D image showing the lakebed¡¯s topography and the locations of relics. Analysis of the image led to the discovery of the 25-centimeter-tall piece of pottery shaped like an artillery shell.

The prefectural government believes that this piece of earthenware was used to boil things, given that it was likely an oshigata-mon doki, a type of pottery characterized by repeated patterns on its surface.

Six Haji pottery jars made in the mid-Kofun period in the 5th century and one piece of pottery from an unknown period were found nearby. Three of the six jars were found lying in single file, suggesting that they were part of a ship¡¯s cargo that fell overboard.

The Shiga government plans to keep the artifacts where they are.

¡°It¡¯s extremely rare to find earthenware more than 10,000 years old in the almost complete condition close to its original state,¡± said Takahiko Fukunishi of the prefectural government¡¯s cultural assets division.

¡°It may have remained intact because it was in the water and not exposed to the air,¡± he added.

Lake Biwa is home to 78 underwater archaeological sites.

The Tsuzuraozaki site was discovered in 1924 when ancient pottery was caught up in a fishery operator¡¯s net. About 200 pieces of earthenware from the early Jomon period to the late Heian period have been found at the site so far.