They are creatures of lost space that developed a lot during evolution along the years, they are here to stay.
They started as just sentinent void blobs that kept getting more intelligent as individuals as time went slowly, and finally got an appropriate vessel shape as well as prime consciousness when they found the humans.
As for the visualizers, they used to be useless marks that came from evolution back then, they could look like the equivalent of birth marks for humans, that until they found a way to make them out for more cosmetic use, so they looked at the humans again and their creations this time, they made an audio visualizer out of them that plays along their voices or whatever music or scenario is playing in their heads (Possible due to prime consciousness developed by evolution as said previously).