The Sun is the roundest natural object measured so far. In fact, if it were to be scaled down to the size of a beach ball, it would be so perfectly spherical that the difference between the widest and narrowest diameters would be no greater than the width of a human hair. To be exact, if the diameter of the solar sphere were a meter, its equatorial diameter would only be 17 millionths of a meter greater than the diameter running from the north pole to the south pole that also coincides with its rotational axis.
On the other hand, investigators at the Imperial College of London concluded that the electron may be the most perfect sphere in the Universe. What separates these subatomic particles from absolute roundness is less than 0,000000000000000000000000001 cm, an insignificant value. In other words, <<if you imagine blowing up the electron so that it is the size of the Solar System, then it is spherical to within the width of a human hair>> says Edward Hinds, head of the team responsible for the measurements. The research has been published in Nature.
Furthermore, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), in Australia, has spent several years developing the most perfect sphere imaginable: it will be a pure silicon object the size of a petanque ball and will weigh exactly one kilogram.
Moreover, pearls are spheres made of nacre produced within the soft body of some mollusks, especially bivalves, around other particles that enter the animals body. The best-known pearls are considered gems or precious stones for their symmetry and characteristic luster. Precious pearls are produced in vast majority by oysters pertaining to the Pteriidae family.