Tendao: Tendao is a large ocean-covered world, comparatively ancient and poor in heavy elements. The planet’s crust is quite porous, allowing circulation between the ocean and the hot mantle, resulting in many hydrothermal vents, but few full-blown volcanoes. At some point in the distant past, Tendao was more tectonically active than it is now, and a large part of its surface is dominated by a vast equatorial plateau that was thrust up high above the surrounding deep-water basins, forming a single supercontinent. Though tectonic activity has since greatly reduced, the planet continued to warm over the millennia, and sea levels rose to cover the supercontinent. Only the peaks of the vast southern mountain range still rise above the surface of the planet-wide ocean; wave action has eroded all other dry land below the surface. Today, Tendao has especially warm and calm weather, especially in the crystal-clear seas of the central plateau; stronger currents in the deeper water carry nutrients and warmth even to the poles, which are ice-free year round. The planet has negligible axial tilt, and so very little seasonal variation in weather. The seas of the central plateau are very shallow, making an ideal habitat for the native Phidi and the marine ecosystem which supports them. The deeper waters are largely uninhabited, the Phidi preferring to stay near the surface, away from the deeps and the large predators that still lurk there. Though Tendao is poor in heavy metals and industrial minerals, it is abundant in Opil Crystal, a rare and exotic substance that is formed in the plateau’s unique hydrothermal calderas, from which hot water rich in light minerals constantly bubbles. Opil is a key trade good for the Phidi, and their settlements tend to cluster around the calderas that produce it. Tendao once had a single distant moon, but it was pulverized at some point in the distant past by an unknown catastrophe. A belt of debris still exists in the moon’s former orbit, and a thin ring of finer debris orbits close to the planet.
Special Planet concepts: