ITT we reveal exciting and completely useless information. I will start.
My cocoa just formed a ring at the top of the foam all by itself! There's a ring around the wall of the mug, then a ring of bare cocoa showing through, like magic... and then a circle of cocoa foam in the middle. There's about 3mm of clearance on this ring! As soon as I drink some, the magic foam ring will be disrupted and it will be gone forever. It's AMAZING AND COMPLETELY USELESS INFORMATION! EVEN TO ME, AND I'M THE ONE DRINKING IT!