Ethmane
this dense gas was found on a few moons and fewer planets throughout the galaxy. When it liquified and froze at the incredibly low temperatures found on remote worlds, it created huge, intricate crystals that were considered among the galaxy's most beautiful natural forms. Worlds such as the tiny moon of Kr were sometimes covered with ethmane jungles, with huge tracts of tree-shaped crystals rising from the surface. Ethmane was also known for its ability to block or absorb sensor systems, which caused problems when flying through the crystalline structures it formed. In its gaseous form, however, ethmane was as transparent to sensors as air.