The reason they say it is a sphere, or a squashed sphere, is because of its immense gravitational pull. A sphere would put all the mass equidistant to the center of the gravitational pull. When dealing with such large amounts of force, any odd shapes that would put part of the mass in an imbalanced form could not be held fast for even an infintely small period of time.

-Weakling
(w_e_a_k@hotmail.com)