Geometrical formulas related to the sphere, which is the set of all points equidistant from a single point in three dimentional space.
Why does this need to be here, you might ask? Well, since softlinks are transient and these nodes do form a logical grouping, it seemed appropriate. Also, they fall far from the top of the list of results for the word 'sphere', which in turn only appear if the 'Ignore Exact Match' box is checked. It was also cordelia's suggestion.