I love the thread at Quora asking users to post their favorite iconic and/or beautiful scientific images. Why? Because, while the usual suspects are certainly present and accounted for (O hai, NASA archives! I can haz Mandlebrot sets?) there's also plenty of images that are at once striking, beautiful, and not at all what you would have expected people to post.

Take, for instance, this image. Posted by Alicia Zha, it was first published by neuroscientist Wilder Penfield in 1950, as a way of illustrating connections between parts of the brain and the physical movements they seemed to control, like a pictorial atlas of the cerebral cortex. It's called the motor homunculus. And it's definitely iconic, even if it's not the kind of iconic that's liable to turn up on the evening news.

Other high points of the thread: Robert Hooke's illustrations of the cell structure of cork; the chemical structure of benzene; group photos from the first world physics conference; and early visualizations of model storm systems.

What would you add?