This is the molecule that makes blood red, and breathing worthwhile. Each hemoglobin carries oxygen, four atoms at a time, from lungs to wherever they're needed in the body. Four heme structures are at the heart of it, each built around an iron atom, forming an interesting rotational symmetry.

It's also a star of science history. With its close relative myoglobin, it was the first protein whose 3D form was verified by X-ray crystallography. Max Perutz and John Kendrew got the Nobel Prize in 1962 for figuring it out, which they did without the aid of computer models of any kind.

Data for this sculpture comes from the Protein Data Bank, where several hemoglobin structures are available. This one is 1A0Z, due to Dr. Arthur Arnone at the University of Iowa.