This morning I dreamt I was presented with a small sphere of shiny, translucent glass or plastic. I set it spinning like a top on a level surface, and it spun rather slowly, wandering around a little but basically staying within a small area. Gradually it lost momentum and began to slow down -- then, intriguingly enough, it began to speed up again by itself. This was explained in the dream as a consequence of its having a little metal bearing inside, which was still spinning at a high rate and imparted its momentum to the shell which contained it.
This evening I was surfing the web at random, looking for anything interesting, when I came across a video clip of something called a Levitating Melting Induction Furnace. It showed a cone-shaped copper coil, within which a small iron pellet was magnetically levitated, and the electromagnetic interaction between them caused the iron pellet to spin and heat up until it was white-hot. I suppose left to itself, the iron might well have continued to heat up until it melted in midair and spewed molten iron around it, but the off-frame operator cut the power before that could happen.
Anyway, I had forgotten about the dream, but the memory of it came back as I watched the video, and I recognized the glowing pellet which spun by itself as an analog of the shiny marble which spun by itself. The usual pattern of first seeing something in a dream, then seeing the image replayed on a screen the next day was repeated.