Archaeologists have discovered a 2,400-year-old filter that was used to extract salt from seawater in North China.
Ancient Chinese in coastal areas used to extract salt from seawater, by using a filter that would be placed under a caldron containing seawater blended with plant ash, said Wang Lingfeng, director of the office for protection of cultural relics in Haixing County, Cangzhou City of Hebei Province.
The filter is believed to be from the Spring and Autumn Period (770 BC-476 BC) and was in good condition when it was found in Haixing County, Wang said.
This sounds really neat, but there are no pictures.