long before Pokemon ADnD went through its stoopid monster phase and this was one of them.
if you're wondering they are a blue green colour with purplish undersides but redden when angry or excited.
I like fogs and seem to use them quite often. The cadaver animating Zombie Fog is a sentient creature in its own right and as it can't be turned a great way to screw clerics. I also use poison fogs and fae mists and in one setting redesigned Elfs into vampiric creatures formed from mist who must leech the 'substance' of mortals in order to gain a physical body (sort of like Leanan Sidhe but the victim becomes mist and merges with The Fog (unless they can escape the overwhelming despair)...)
also it's becoming increasingly difficult to find a unique Z without resorting to different types of Zombie! So next rounds a challenge