Metaphor. Chestnuts are very strange in shape, like a hedgehog. It uses a metaphor to explain, comparing chestnuts to hedgehogs. Chestnut actually refers to chestnut, which is a common food, known as the "king of dried fruits" and one of the specialties of China. Moreover, it has extremely high nutritional value and is deeply loved by people. It is also called "ginseng fruit" abroad.