One good, and fine day, I was playing minecraft. I loaded up a world that I was working on. The first thing I actually saw when I entered the world was just my creations. I saw a horse on a tall skyscraper, with the name 'Entity 0'
It was locked in place, like an anchor holding it down. Then it quickly glanced at me and disappeared. I started to encounter weird things like a sign on buildings saying "Entity 0"
The very next day I came back to the same world. Everything was gone. One block of TNT was on the floor. Next to it, it said: "Entity 0"