Landlord, first of all, Wan Wen walnuts are very different from the walnuts we usually eat, one is for eating and the other is for collecting. Just like snuff bottles and medicine bottles, they are actually the same, but since the rise of snuff, people have found that medicine bottles are suitable for holding snuff, and their value has gone up. In the Qing dynasty, a medicine bottle could not even be bought, and the store could still give it to you, which was worthless. Of course, my personal understanding is that Wan Wen's walnut shell is hard, some lines are strange, and the shell is thicker than ordinary walnuts. After playing with it, it will become as beautiful as a jewel, with patina. Wan Wen walnut, after decades of playing, due to the chemical reaction of human sweat and oil, gives birth to patina, and gradually becomes as beautiful as jade, unlike walnut. Of course, there will be more people who like it, and there will be more people who want to collect it or make a pair themselves. Online pictures can be searched, a lot. Specifically, you can buy a book or go to a related forum, because there is so much knowledge in it that I can't explain it to you one by one.