Used to dig up rhizomes, such tools are usually large and rough. They are made from a huge, thick and flat piece of stone, worked on the smooth side to create a sharp ridge or hump on its back. These tools have been found at sites in Xihoudu and alongside the Ke River, dating back approximately 1.8 million years and 700,000 to 800,000 years, respectively. They have also been found at Lower Neolithic sites in Huairen Emaokou, Shanxi Province. Well-known Chinese anthropologist Professor Jia Lanpo regarded them as representative stone tools and important material evidence of the Ke River-Ding Village culture.