An alien species of unknown origin that floats in deep space in search of planets to live on. Once subjected to the gravity and atmosphere of a planet, it rapidly absorbers the elements the planet is made from and grows large enough to cover the entire surface of the planet. Once it engulfs the entire planet, it absorbs it entirely, including the core, which can take millions of years. Once the planet is no more, it's large enough to generate its own gravity field and drifts through deep space or orbits a nearby sun looking for more planets and moons to grow larger. While it is able to cool a planet core down to an absorbable temperature, its only natural death is getting pulled directly into a collision path with a sun.