Earth

Earth is a water-based planet, inhabited by a range of species, though dominated by humans. ("The Lake Nose Monster," et al) Earth is a well known planet in the galaxy, and several sentients are familiar with the human race. The planet grew to an even more immense size alongside the galaxy, due to an invention of inhabitant Heinz Doofenshmirtz. The human race remained oblivious to it, however, as everything appeared the same. ("Out to Launch," "The Chronicles of Meap," "Attack of the 50 Foot Sister")