From new.math.uiuc.edu/oldnew/calculart/ This surface is a Whitney-stable 3D projection of a nonorientable surface with Euler characteristic 0 (a Kleinbottle) embedded in 4-space. Like Steiner's Roman Surface, the Etruscan Venus loses its singularities under François Apéry's Romboy homotopy and becomes an immersed surface equivalent to the connected sum of two copies of Boy's Surface.