In the sea there are many islands(岛). In its warm waters, there are some little ones. We call them "Coral(珊瑚)Island".
A coral island is very nice to look at. It looks like a ring(环状物)of land with trees, grass and flowers on it. One part of the ring is open to the water. There is a little round lake in the island.
If you look into this lake, you will see beautiful corals. You may think they're flowers.
If you look at a piece of coral, you will see many little holes in it. In each of these holes lives a very small sea animal. These sea animals make the coral.
They begin to build under the water. Year after year, the coral grows higher and higher. At last it grows out of water.
Then the sea brings to it small trees and some other things. In some years, these things change into earth. Sometimes the wind brings seeds to this earth. Sometimes birds fly over it and bring seeds to the island. The little seeds grow. In a few years, there are plants all over the island. In a few more years there are trees growing there. So you see, these islands forms（形成） little by little. The workers are very small. Don't they teach us a lesson? Can you think what the lesson is?
