A crystal sphere, also known as a crystal shell, is an object of great size that surrounds an entire planetary system and forms a boundary that separates wildspace from the phlogiston. The size of crystal spheres is related to the size of the planetary system within them. As the name 'crystal sphere' implies, the objects are spherical. Although they are solid, crystal spheres have no gravity and no atmosphere. The material crystal spheres are made of is a unbreakable dark ceramic material. No magic is powerful enough to damage crystal spheres.