Image: Richard Ling （Wikipedia）
WHERE does sand come from? There are many sources. But the one described in this article might surprise you. It is a fish that grinds coral into fine sand—the parrot fish!海沙是从哪里来的呢？来源有很多。这篇文章会介绍其中一个，可能是你意想不到的。有一种鱼会把珊瑚磨成细沙，它就是鹦嘴鱼。
Parrot fish usually sleep concealed under a ledge, but such a hiding place will not always protect them from a hungry shark.
For additional safety, some parrot fish wrap themselves up for the night. They secrete a protective mucus that envelops them, looking somewhat like a transparent nightgown. Marine scientists believe that this foul-smelling wrapping protects them from predators.