Here is my idea for the Bugger's Queen from Orson Scott Card series. First two books had no clear description of the buggers so I am going from my general impression and some bits of information. First, this is a some sort of a bug with some strong ant influence hence the overall appearance. Buggers have a way of instant communication between each other regardless of the distance so the grown-in headpiece is my idea for that bio-machine integrated into the body. Instantaneous communication allows the queen to control all the buggers and be their brain. So the size represents the massive amount of communication that goes on between the queen and all the other buggers. Just got the Third book Xenocide, so my vision might change...given I'll be able to finish it.