I'm sure you already know Kim Asendorf (@kimasendorf) or you have already seen his works around internet. I love his projects which always have an abstract, minimal, and geometric aesthetics, you can check it in his last exercise called "638".
Asendorf is doing a little Processing workshop each monday in the Art School Kassel, this time he showed the students how to make gifs with Processing and the gifAnimation library by extrapixel . With this flow he did this gif series, these are programmed, a circle aligned to the center of the canvas gets a random size and color. A simple loop tween makes it as large as possible (256px) and then back to zero pixel and again to the starting value. The same happens with the color and also the alpha value. By using more than 1 circle something like a wormhole appears. and if you want, it also feels like the circles rotates like vinyl on a turntable.
The file name explains the content a little;
c00-10-128-bw.gif = name-circles-frames-animatedColorValue.gif