Ominous fixed-point cubes

The ominous fixed-point cubes are strange, cubical, black solids located at precise coordinates with respect to the center of the planet. They are utterly immovable, hovering in the air whenever the land falls out from under them. They rotate with the planet, though over the centuries they have been found not to track the tectonic plates, resulting in an apparent movement of the cubes at the rate of continental drift. This occasionally causes trouble for long-term human structures near a fixed-point cube. The historic cathedral in the Shastrian mountain town of Coilon has to be moved before the end of the century, as it was built underneath a massive cube that has been slowly descending to ground level as plate buckling raises the town's elevation. Similarly, the city of San-Seintil in Ouril was abandoned in the eighth century when a cube surfaced through the foundation of the nearby dam, flooding it. Seemingly innocuous cubes can pose trouble, too. While the larger ones are easily visible, smaller ones at higher altitudes have been known to take out inattentive airplanes, and the Taurus Research Station has had several narrow misses with featureless black cubes nearly tearing holes straight through the station.

Nobody knows where the cubes come from. Some are sheer and blank, while others have minute geometrical patterns inscribed on their faces. Until around a century ago, despite the ramblings of penny dreadfuls, it was thought that the cubes just were, and had no more purpose to them than any other feature of the landscape. This assumption was challenged by the illustrious Dr. Stafford, who scribed a formula that could be solved for the locations of every fixed-point cube on the planet. As usual, nobody really knows what the formula means or how he came up with it, but it is accurate for all known cubes and has successfully predicted the locations of cubes then undiscovered. Stafford's brilliant formula put to rest one centuries-old fear: that there might be a large fixed-point cube in Zor Olo's orbit, and that when Zor Olo crashes into it, whatever is inside of it will be freed. It did this at the cost of replacing it with a new fear, that of a predicted cube larger than the planet itself and a vast astronomical distance. I'm told it already has a cult in Kingsland.

The cubes' complete and total immovability has made them a metaphor throughout the ages for those facets of life which must be accepted as they are and cannot be changed. Ever since civilization figured out that continental drift makes them "move" slowly across the surface, they've also become harbingers of the inevitable. This makes it easy to, say, put a fake cube on the good couch in the Butterfly Effect Advisory Committee break room to keep certain unnamed individuals from sleeping on it.