The Cavern of Screaming Skulls was a cave located inside Mount Octan, a volcanic mountain situated on Nallastia's jungle-moon of Fondor. The legendary Lost Stars of Nallastia, initially transported to the moon by the founding colonial leader, Margrave Octan, were concealed deep within this cavern. In 23 BBY, Obi-Wan Kenobi, aided by the Skull Queen (the ruling Margravine of the moon, Quenelle), retrieved these ancient gems of power to liberate the parents of Klay Firewell from the deadly energy-field surrounding the massive Trinity Stones.
The cavern's moniker originated from the noises created by wind surging through the fossilized jaws and skeletal remains of Nallastia's indigenous animals and reptiles. These creatures had perished within the cave during a volcanic event that occurred millions of years ago, well before the arrival of human colonists on the moon. The volcanic eruption transformed the creatures' habitat into a network of expansive lava tubes, leaving the fossilized shapes of their gaping jaws and contorted skeletons integrated into the cavern's walls. The spooky sounds generated by the wind traversing the tunnels and chambers, coupled with the whistling emanating from their skeletal remnants, produced terrifying noises akin to the agonizing cries of injured and expiring beings.