This is a collection of small works we released some years ago for community initiatives. They're all licensed under CC-BY-SA, which means you can do what you want as long as you credit the original authors.
The wallpapers listed down is work done by pmworks for the Spread Firefox community initative, while the icon(s) was released by pmworks as a contribution to Wikipedia.
Firefox - Burning the Universe
This is the second version of Firefox Space Reborn. The original wallpaper is available at this link.
Originally created for the SpreadFirefox community together with Nadir - Firefox Bite, the second image below, this is one of the 100 most selected/featured Firefox wallpapers.
Firefox - Duke përmirësuar jetat tona
Not as successful as the others, this wallpaper is actually very popular in the Albanian community. (Try searching for albanian wallpapers)
Nadir - Firefox Bite
As for Firefox - Burning the Universe, first wallpaper above, this is also one of the 100 most famous Firefox wallpapers on the entire Web!