Fiction:The Firmament/Plane of Earth

The Plane of Earth is one of the four regions of the Elemental Plane, currently ruled by the monolithic elemental lord Umberien.

Description
The Plane of Earth is composed primarily of rock and earth, covered in veins of precious metal and gemstones of such gigantic proportions that they cannot be believed by those who have never set foot there. Interspersed with this solid rock and earth are caverns of all sizes, some of them dark and dry, others filled with water and phosphorescent fungus. Others yet are lit by enormous crystals, enchanted by the native creatures to illuminate vast caves, like miniature suns.

Inhabitants
Earth elementals call the Plane of Earth their home, and unlike most elementals, they are considered more tolerant to outsiders, though still react violently to the presence of rival creatures from other Elemental Planes. The Plane of Earth is arguably the most inhabitable of the four to outsiders, making it the most common stop to planar travelers.

The crystal wyrms are the True Wyrms native to the Plane of Earth.