After the walnuts are picked from the trees, they must be piled up and retted, peeled off to reveal the walnuts with hard shells inside, and then the hard shells can be opened for eating.

Walnuts growing on trees are turquoise, with a thick green skin outside, which is poisonous. Therefore, green-skinned walnuts should be piled on the ground after picking. After the thick skin outside rots, walnuts with hard shells inside are exposed, that is, walnuts sold in the market, so that the hard shells can be opened first and then the pulp inside can be eaten.