@AlexO6: Go That tentacle thing is called Zerus Tree Viper, it's a critter and as the name suggests will be found on Zerus. I think it may be incorporated into the swarm somwhow, unlocking an upgrade or unit evolution. The Viper's "head" is extremely similar to that Bane Creeper fan artwork in SC2 site.
Your private fistpump will go unnoticed when you play the campaign and reach the Zerus level to find that the bonus objective is to assimilate tree vipers in order to unlock a unit upgrade in ship-mode.
Hots Custom maps were forbidden by Blizzard.
They asked the mapmakers to take them down as they can confuse players about what HotS is and in which state it is.
The maps had to be removed before 4th September.
I'm bringing this thread back because some new stuff appeared in the beta files before they shut it down. I found one of the Mutas evolutions and it's named Viper in the unit icon, which is weird because the tail does look like the Viper's tail. Two other models are called Protoss Snake Head and Protoss Snake Segment, and you can see the head is a heavily modified Carrier, it even uses the standard carrier textures. I believe these 2 might appear in a new version of the Lost Viking mini game, maybe a new blizzard mod? The textures for the segment are called GlaiveTron.