While you were tweeting about feral hogs last night, I sat transfixed, staring at this video of a three-dimensional arrow that can’t point left. Really:

　　The arrow sculpture, which you can apparently buy online, was designed by Japanese mathematician Kokichi Sugihara. Sugihara specializes in creating these kind of spatial illusions that use variations in perspective and optics to manipulate our impression of the objects’ shapes. Here’s a bit more of his work:

　　If you’re into this kind of thing, the Neural Correlate Society holds an annual competition to crown the Best Illusion Of The Year. Enjoy that rabbit hole.