Heart of the Planet is where you will battle Zarkhator for the fate of your planet.
The Heart of the Planet is a location found in Spore Hero, and the final location the Sporeling reaches in the story. It is found in the Creature Beach, and it is actually a colossal creature found laying around a rock wall on sand. It is where the Sporeling first races Zarkhator to get to the Ancient Brain. Later, when Zarkhator reaches the Ancient Heart, he and the Sporeling goes here to have a final battle against him to determine the fate of its planet.