It was found 10 meters underground? In a crop field? WTF? Just how deep does this farmer plant his seed?
He must have been digging it for something. Hunting treasure, or digging a well?
"Just how deep does this farmer plant his seed?"
You should probably ask his wife, but based on stereotypes, I'd say about 2" deep.
Just a joke!
Remember what the crop of choice is in that region. Rice grows in mud.
In 1978, I was a part of the RED HORSE construction squadron in Osan Korea. We excavated a rice paddy down 27 feet in some places to get to solid ground. Then we filled it up with concrete to make a quick turn facility at the end of the runway.