美国科学60秒 SSS 2013-06-27（在线收听）

 　　Flawless pearls are among the most symmetrical spheres biological organs. But do they get so round? Turns out they turn. Pearls and mollusks such as oysters create so-called pearls acs around intrusive pieces of grit. The sac coat the yelten with the layer smooth biker also known as mother of pearls. The growing pearls rotate itself which allows the biker to deposit even they over its surface.By examining pearls under influences and scanning electronic microscope, researcher discovered that the surface actually has soft tooth texture. As the mollusk moves, the pearls flaw so to the next tiny tooth. The works is published in the Journal Lanier. A pearl' motion influences its niker coverage and not its finally shape. Depending on its surface pattern, it might turn in a single direction to create a drop or ring, or rotate more freely to form sphere, if defect prevents this motion, the final product will be shapeless. The resulting asymmetrical pearls is doomed to be booed.