Snail's eyes are located in the head of the front part of the body and have two specific positions-the base of the antenna and the antenna. Usually, snails with a pair of antennae, such as mountain snails and bean snails, have their eyes at the base of the antennae; Snails with two pairs of antennae, such as African snails and Swinhouse snails, have their eyes at the top of the big antennae. To the naked eye, the snail's eyes are just two small black spots. In fact, the snail's eyes are similar to human beings, and they are also composed of cornea, lens, retina and optic nerve, but the structure is very simple, so the snail can only judge the surrounding objects by feeling the change of light, but can't really see the appearance of objects like the human eye. So snails have poor eyesight. But for snails, eyes are not very important, because they usually move at night and don't use them often. However, if you touch the snail's eyes with your fingers, it will immediately retract its eyes into its shell. Even if the eyes retract into the shell, the snail can observe the outside through the reflection of light from the shell wall. Inspired by this, scientists invented the earliest gastroscope to treat stomach diseases. Some snails can be eaten