This surprising surface was constructed by Francisco López in 1993. It has a single Enneper end and total curvature -8π. López proved later that it is the only minimal Klein bottle of total curvature -8π. The surface is parametrized on its oriented double cover, a torus with two ends.
F. López: A Complete Minimal Klein Bottle in R³, Duke Math. Journal 71, 1993, 23-30