A fisherman caught a large pearl from the sea and couldn't put it down. However, the pearl has a small black spot on it. The fisherman thought that if the little black dots could be removed, the pearl would become a priceless treasure. So, it scraped off the black spots with a knife. However, after scraping off one layer, the black spots are still there, and after another layer, the black spots are still there, and at the end, the black spots are gone, and the pearls no longer exist. Peo...