I have more than one ideas but they all go in similar ways

"The Halocals" -> Derivating from the HALOCARBON-14, a potent greenhouse gas with a very high bond strenght. My idea is that this ancient civilization apears in worlds which population has developed machines who pollute their atmosphere. They fuse with the polution, they observe, they learn and assimilate the tech of the population of the planet. Their native planets are the High density gas planets where they were born. The idea is they can observe and fuse with a planet so as the greenhouse gas do with our planets just nowadays. This gasses are capable of swaping density to move between diferent heights in atmosphere, and their spaceships could be just void rocks. The idea of the ships beiing void rocks is to help them keep stealthy and don´t be detectable to other factions when they are orbitating their systems. Just some crazy Idea...

"The Kriptionians" -> I know, cheap idea. But Kripton is an invisible, inodore and technicaly inert gas... But what if it is not that inert? It fits me i don´t know.

As you may see I am going in the scientific branch searching for a name... Other options are "Radonians", "Xenon Whatchers", "Silaniars" coming from the Radon, Xenon and Silane gases.

Sorry for my bad english