Majin Bone Season 1 Episode 36 Rare Metal Bone

Dark Ouroboros's attacks have taken out Dark Wyvern. From outside the Cocoon, Stolz, worried about Dark Wyvern's adept, Klude, finds himself thinking back to the time Klude recovered a certain Bone that served as a certain planet's core. Klude's recovery of the core Bone resulted in that planet's destruction.