The Cave of Elders was the only artificial structure in the ThonBoka, a nebula located within the remote Open Sea in the Centrality. Believed to be the only structure ever constructed by the native Oswaft species, the Cave of Elders served as an important meeting place for the Oswaft. Constructed between the three small stars at the center of the nebula, the Cave of Elders was a 20-kilometer rotating sphere entirely made of precious gems, and was built to be an exacting replica of the ThonBoka as a whole.