A surface of revolution defined by Kepler. It consists of more than half of a circular arc rotated about an axis passing through the endpoints of the arc. The equations of the upper and lower boundaries in the x-z plane are z_± = ± sqrt(R^2 - (x - r)^2) for R>r and x element [-(r + R), r + R]. It is the outside surface of a spindle torus. It is also a quartic surface given by Cartesian equation (r^2 - R^2 + x^2 + y^2 + z^2)^2 = 4r^2(x^2 + y^2) or r^4 - 2r^2(R^2 + x^2 + y^2 - z^2) + (-R^2 + x^2 + y^2 + z^2)^2 = 0.

bubble | lemon surface | oblate spheroid | snake | sphere-sphere intersection | spindle torus