What is the reason for a grain of stool

Normal people's stools are generally 1~3 times a day, or 1~3 days solution. As long as the stool is not very dry, and is not very thin are considered normal stools. Normal people are mostly formed, soft "banana stool", is strip, formed. But constipation patients are different, will solve hard blocks, induration, dry blocks. Some people will block relatively large, can see 3~4 cm large induration. And some patients with constipation for a long time is small, so commonly known as sheep feces egg-like stool. Some patients with constipation are showing round granular, but relatively hard, even fall into the urinal can make a sound. This is constipation in some patients in different forms.