The following is a summary of the eversion: 1. sphere: green outside, red inside... 2. transforms into... 3.
The Morin surface has a quadruple point through which passes its axis of symmetry.
The diagram shows section East bounded by three loops: ABCDA, AEFGA, and AHIJA.
The third loop, AHIJA, is a line of double points where section East intersects with itself.
Morin surface can be elegantly described by a set of equations[1] in either open version (with poles sent to infinity) or closed.