Why do some people call watermelon "the ball in the kalahari desert"?

In hot summer, people are often thirsty. If you can eat some sand and sweet watermelon at this time, don't mention how comfortable it is. Do you like watermelons, children? Watermelon is not only delicious, but also has the ability of relieving summer heat, relieving fever and diuresis, which can help people alleviate many diseases. So you want to know how the earliest watermelons came from? Who found it again?

More than one hundred years ago, a traveler named Livingston came to kalahari desert. He happened to find that there were many small fruits like balls in this deserted desert. Groups of elephants, rhinoceroses, lions, antelopes and other animals like to eat it very much. This is our favorite watermelon now. Because it was discovered by Livingston in kalahari desert, people nicknamed it "the ball in the kalahari desert".