Zeona

Description
Zeona has a thin atmosphere of sulfur dioxide and trioxide, created by volcanic outgassing. There are traces of water vapor in the atmosphere, but over the last five centuries of observation particle counts have decreased 4%.

While not habitable by any spacefaring species, there is an abundance of native sulfur-devouring bacteria that thrives around the world's many volcanic vents. Interestingly, these bacterium bear genetic similarities to the native life of Illium, suggesting either a "panspermia" spread of microbes via asteroids, or accidental contamination of the original environment by careless spacefarers.