The Alien Turtle! (this picture is bad,i know :D )
The commander can spawn the turtle for 40 ress,then he build whips,crags and/or shade on it. Gorges can build hydras on the turtle.
The turtle is very slow but it has a good def.
The commander can control the turtle like a arc. He can "deploy" it,it means the turtle hiding in the turtlearmor so it have very good defend but it can't move. He can "undeploy" it,this means the turtle can walk but the marines can shoot at the head of the turtle.
If the turtle die only the armor ,with the things on it,is lying there and now it have no infestation and the whips,hydras and other things do nothing. If the turtle alive it has his own infestion on it and it needn't to be connectet with a hive.
I hope you enjoy the picture,and sry for my bad english ;)