Around nine feet in diameter, one Bosnian archaeologist claims that it may be the oldest stone sphere created by humans and perhaps evidence of a lost civilisation. Other experts have dismissed this as nonsense and even that it may have been created by natural processes.
Whatever the truth, it could provide GMs with the basis of an adventure. Is it an alien artefact? Is it a Silurian device and disturbing it will awaken the colony in hibernation below? Could it be the shell of a hitherto unknown, ancient lifeform, dormant but still alive? Or is it just a hoax, and if so to what purpose?