User blog comment:JERealize/Arena Idea Now On Sale/@comment-3466333-20120426011948

Planets are usually formed by molten rock cooling and condensing or a remains of a larger planetary body being regathered. The gravitational pull makes this a solid object. We have a molten core because the outer layer cools faster, obviously. If we were to remove the core, our planet would loose subterranean heat and the geothermal-biotic creatures would die. Plus, the planet would collapse. But I still like your idea!