Dr. Hinke Osinga and Professor Bernd Krauskopf crocheted this magnificent Lorenz manifold, "the two dimensional stable manifold of the origin of the Lorenz system".
The final result consists of 25,511 crochet stitches and took Osinga about 85 hours to complete. However, this wasn't just done for fun. Their work gives insight into how chaos arises and is organised in systems as diverse as chemical reactions, biological networks and even your kitchen mixer.
Link - there's even an instruction on how to do it, if crotchet & math are your things. (Thanks Jen!)