A 3-dimensional cubical lattice
When you drive past a farm with plants in a rectangular grid, you'll see flickering lines as they momentarily line up in various ways. Here you can see that in 3 dimensions.
If you were standing in a rotating space filled with dots, one dot at each point with integer coordinates, this is what you'd see.
It's all about number theory. Suppose you have a farm with one plant at each point (x,y) where x and y are integers. Then you'll clearly see lines of plants with slopes y/x when y and x are small integers. So, slopes like 0/1, 1/1, 1/2, 2/3 and so on. There will also be lines where y and x are large integers, but these will be harder to see.
The same sort of thing happens in 3 dimensions. See all the ways the dots line up?
But notice, you're not shooting past these dots like driving past a farm. The dots in front are moving left. The dots in back are moving right!
So, I think these dots are actually rotating around a vertical axis. If take a dot that's not too close, and not too far, and follow it with your eye, you can see it go round and round! It's a bit hard to do, but it's fun to try.
This image is one of "Charlie's daily sketches":http://bigblueboo.tumblr.com/post/110725892760/drift-matrix