Space craft of any of our brethren, or of our counterparts, the Service-to-Self, are not round, as in a ball. This is not aerodynamic, nor does this in any other way adhere to the physics required for travel. In addition, this does not make best use of the interior space, as any resident of a circular home will tell you - there is automatic wasted space in the ceiling and floor areas, at a minimum. UFOlogists will report that the crafts reported upon invariably have a flattened or nearly flattened bottom. Circular objects cannot have a stabilized gravity centralization akin to what a flat bottomed craft can. Think about it! A circular object, with a gravity bottom point of one tiny part of the globe, would wobble about! A flat, or relatively flat, bottom gives many points of reference.