Helicoid with a Hole
Obtained in terms of elliptic functions , this minimal surface has two helicoidal ends consisting of a helicoid with a hole and handle; it has genus one and it is invariant under a one-dimensional group of translations.
 D. Hoffman, H. Karcher, and F. Wei. "The Genus One Helicoid and the Minimal Surfaces that Led to Its Discovery in Global Analysis and Modern Mathematics." (1993) www.gang.umass.edu/preprint/documents/gang3-16.pdf.gz.
 M. Weber. "The genus One Helicoid as a Limit of Screw-Motion Invariant Helicoids with Handles." (Jan 6, 2003) www.indiana.edu/~minimal/research/heliclay.pdf.