Thousands of years before the Involved Species' recorded history, an Involucra race named the Veil had created vast spheres from an unknown but highly resilient substance consisting of several layers, interspersed with a tracery of tubes and towers which maintained the spherical integrity of each layer. It was supposed that each of these layers were to contain some form of superfluid, distributed through the great towers, for reasons unknown, though it was supposed that once all the Shell Worlds, which originally numbered over 4000, were activated it would create an energy shield around the whole galaxy. For similarly unknown reasons, the Veil disappeared, leaving the Shell Worlds derelict. Some time later, a race called the Iln attempted, again for reasons quite unknown, to destroy the Sh