Have a look at the Overmind concept by Pevel:
Pevel wrote:New overman:
And a few comments to justify and explain some things:
Sketch number 5 is the 'eye' when it's not glowing. The surface surrounding the center should be smooth (and shiny preferably) - in case it's not apparent.
In the sketch number 6, the brain-like surface may be partially glowing if possible. Plates on the armor should be barely visible.
Perspective is certainly off in some places. I hope it's not that much of an issue. The concept isn't sketched as ideally symmetrical but if the model would end up being symmetrical - it's perfectly ok.
The Overmind, or OM for short, is the alien team's main structure. Without the OM, nothing works properly in the alien world: Evolution is stopped, structures refuse to defend the base, chaos is everywhere! The Overmind will likely use some sort of "psy attack" to harm and/or disorient close humans but it will still rely on base defenses for survival.