| Basic equation given by (z=x2/a2+y2/b2) where a and b are constants.
Cross-sections of the graph parallel to the xy plane are ellipses and cross-sections parallel to the xz and yz planes are parabolas. It looks sort of like a bowl, only it extends to infinity rather than having a brim. This is a standard shape that people first learn in multivariable calculus and such when they actually care about formulas and equations of figures in more than two dimensions. | 
