A total of 20 ground tools with multiple perforations were uncovered though only two were complete. From these it is possible to more or less ascertain their full shape the remainder are mainly fragments. In terms of raw material they were made of slate with flat bodies in a long oval shape. The borders of the two sides were straight or slightly curved inwards. The body of the artifact is finely ground with the periphery well rounded. It seems as though there is a cutting edge at one end though this is not clear as most edges have been grounded smooth with only a few pointed, but also not sharp.
　
　 The distinctive feature of these artifacts is that they have a number of paired-holes generally four, though there have also been samples with as many as ten pairs. At present, it is still not understood how these stone artifacts were used. On the basis of Anderson’s report (Swedish geologist) Kano Tadao that these are related to the sounding stones discovered on the border between china and Outer Mongolia. These are the same shape but differ in terms of size and materials used in their production and so have been called sounding stones (Sung Wen-hsun trans. 1955: 7). As a result of this hypothesis it has been suggested that these artifacts come from Northern China, though other scholars have expressed doubts concerning the veracity of this postulation. More recently, some archaeologists have inferred that these artifacts could be stone shovel and that the perforation are there to tie it to a wooden handle, though this idea has not be unanimously accepted by archaeological circles.