Huh
Took me a while to see what's really there, and then I understood your subject line. We spend a lot of time looking at overhead shots of planetary and lunar surfaces, and it's easy to get fooled. I still sometimes have trouble with the innie-vs-outtie aspect of craters, and those are nothing compared to the optical illusion in the image you posted.
On top of that, it's a beautiful image. Very nice.