A pellet of stool or black is related to constipation, dry heat in the colon, improper diet and other factors. Many people suffer from constipation. When constipation occurs, feces are dry and will form granules because they are stored in the intestines for a relatively long time. The feces will also be overly concentrated after a long time in the intestine, so the color will be darker than usual, and some people will even have black stools. The nutrients in food residues are absorbed and then excreted into the large intestine. The large intestine will expel the stool through peristaltic movement, while absorbing the water and remaining nutrients. Once the dryness of the colon occurs, water is excessively absorbed in the stool, and the stool excreted by these people will be too dry and black in color. Some people have granular stools, black color is due to dietary problems, eating a lot of animal blood, animal liver and other foods, reduce dietary fiber and other foods, not only intestinal peristalsis will be relatively slow, resulting in the formation of granular stools, and because of the large amount of iron in food residues, the feces is mainly black.