I am not a big fan of logos or marketing on my wallpaper, however even I have been using this beauty.
Found it randomly when surfing through Google images looking for something totally un-related. Maybe finding treasures like this is better when you don’t look for it, it just finds you… or perhaps that is a little too deep of a rabbit hole to jump down this early in the morning.
You can pick the wallpaper up at Gnome-Look.org, and I have also seen it here too (just in case that first one give you trouble or goes down).
Nice Wallpaper firefox. iam looking firefox………………