Rondo is the water-based homeworld of the Cresendoins, and it is similar in many ways to Eath in terms of size, overall temperature, and gravity, but Rondo does not have as big a temperature difference between its poles and its equator, meaning that the enitre planet is roughly the same temperature. Not only that, but the planet itself has no islands or land, only seas, because there cannot be any ice on the world.
Rondo is odd in that depsite the fact that it is a warm, water-based, nutrient-rich planet, ithas very little life growing on it. Aside from the Cresendoins very vew other life forms exist there. The Cresendoins eat zooplankton to survive and have no natural defences as the planet is so very dull.