Based on the Invid Shock Troopers from the 3rd war of the Robotech cartoon series. A reference most will not catch! This is actually a model I made MANY years ago, but I just couldn't come up with a secret enemy for the space world, so I looked through my files and found this. Turned out to be the most impossible secret level in the game! Sorry!
It's similar to its successor (Rock Trooper) but instead of shooting rocks, it shoots big yellow orbs of explosive destruction.