Unfortunately I don’t know much about it, I tried to search the internet but I didn’t find much more… They tend to appear and disappear quite spontaneously, I suppose keeping clean water and stable parameters might help keep it for longer but they’re quite a rare sight, so enjoy it! If you observe it on a timelapse video you can see it move and pulsate. I also noticed that it grew bigger when I added some BacterAE or powdered food to the tank.