X'Nelli is the home planet of the Polar Manzardills and several other Manzardill species.
X'Nelli is one of those rare planets in the universe that exists in what is known in scientific circles as the Goldilocks Zone, meaning it is precisely the right distance from the star around which it orbits so that the planet is not too hot, not too cold, but just right. Like Earth, for example.
Unlike Earth, however, X'Nelli has no tilt to its rotational axis, therefore enjoys remarkably stable climate conditions in both hemispheres year-round, with the only exception being the polar ice caps at its northernmost and southernmost points. The unchanging temperate climate of the rest of the planet's surface makes this world particularly perfect for cold-blooded creatures that rely on the temperature of their environment to regulate their own.
Because of this inviting habitat, reptilian aliens are the dominant species on X'Nelli, of which there are many classes or phylum, including the Polar Manzardill, the only known cold-blooded creature in existence whose blood really is cold.