As a pearl might appear unexpectedly in an oyster being shucked, we sometimes find amidst the complex detail a round, perhaps three dimensional and seemingly out of place jewel.
Here we see three "pearls": blue and gold, and in the center a "rainbow pearl" which shows the all the colors in the spectrum around a zero. We will later see rainbow pearls with a central pole.
In this case the "pearls" look more like "shells."
Pearls around a pole tend to become "eyes."
"Planets" are also round but their galactic surroundings distinguish them from pearls.