Hogof

Hogof is a largely barren world orbitting the red dwarf Serenna in the Perseus Arm. The surface is a rocky, barren wasteland with little atmosphere. However, below the surface is a massive network of caves which extend all the way to the core. The lower levels are warmed by geothermal heat and boom with life. The magma, which has remained rather stagnant since the planet was formed, provides a light and heat source to the life forms here. Although lighting is dim, creatures here have adapted to have sharp vision and large ears

The upper levels near the surface are quite dark and are much like caves of most worlds. The creatures here must rely on hearing to navigate the dark caves. To date, no entrances to these caves from the surface have been found as dust and debris have blocked off the most likely areas.

History
The planet is believed to be about 8 billion years old. Life used to exist on the surface, but the climate became unstable when the ozone layer disappeared along with most of the atmosphere. Anything that wasn't killed by ultraviolet radiation did not live much longer when temperatures became extremely high during the day and low at night.

Ice caps were once present on the planet, though they melted away, seeping underground. The groundwater along with these ice caps created the enormous cave system where new life now resides. The new tunnels interconnected with more caverns which were isolated previously.

Modern Inhabitants
The planet's cave systems are inhabited by the sapient Breswyldd. They come in two variants: the Isela are those who live in the lower levels near the core. The Tal live in the darker, upper areas and are blind.

Discovery
The planet was assumed to be barren and was being used as a test area for short range teleportation by the Dhragolon onto worlds with dangerous surfaces. A slight miscalculation to the teleport destination sent a team of Dhragolon into the underground cave system where they discovered the booming ecosystem. Seeing as this subterranean world would be threatened if a hole from the surface was bore, the Dhragolon declared that teleportation would be the only way to and from this world.