The Primus Gruntus Maximus is the male parent of all living members of the Grunt Species. He evolved from the Gruntus Not Quite Us and, supposedly, the NeanderGrunt.
He is the largest Grunt, has the ability to float and is seemingly mute. All Grunts are born, or hatch, from warts on his back.
Before the creation of the Brotherhood of Grunt he was seemingly floating around aimlessly while grunt hatchlings fell from his body to the ground below. However the 5th of Kevin managed to not fall off and grow to maturity on his back. He then build the Monastery to provide the Primus Gruntus Maximus with a home.