A Triceraton Mobile Homeworld.
The Triceraton homeworld was destroyed and broke into pieces, leaving Triceratons to rely on mobile homeworlds which are large flying stations that incorporate cities within them, becoming the mobile homes and battle stations of the Triceratons. These homeworlds can be seen in the Mirage Comics, 2003 TV Series and Teenage Mutant Ninja Turtles 2: Battle Nexus. You fight one of them as a boss in the GBA version of the game.