We often talk about snails (蜗牛) and their slow move. But usually snails don't move at all. They are in their shells(壳)— sleeping.
Hot sun will dry out a snail's body. So when it is very hot, a snail draws(移动) its body into his shell. A snail will die in a heavy rain. So when it rains, a snail does the same thing, too. A snail can sleep for a long time. It spends all the winter in its shell, sleeping.
In spring, the snail wakes up. Its body is only about 007 meter long out of the shell. When hungry, the snail looks for food. Its eyes are not very good. But it does very well in smell. This helps the snail to find food and the new plants.
A snail's mouth is no bigger than a full stop(句号). But it has 256,000 teeth! The teeth are very small, and you can't see them. And if its teeth are too old, it will grow new ones.