In legend, a witch usually has a crystal ball with supernatural power. With the development of science and technology, the crystal ball may really come true one day.
The strange sphere hanging on the wall has the similar effect of the crystal ball in legend by taking advantage of the modern interactive technology.
Now let's have a look at this "crystal ball" through a video:
Drill-down:
It is used to describe articles that are stemmed from a single lead article that give a more in-depth or detailed information of the same subject.
