A certain black hole singularity is an artificial creation of Iblis, leading to a world where his followers had been first exiled after being being cast out by the Seraphs untold thousands of yahrens prior.
This black hole bridges the Colonial's known universe and a separate universe, ensnaring many hapless denizens for an untold period of time due to its devastating effects on ships that pass through it. The fact that it "hides" in normal space only to be "sprung" on unsuspecting ships is unnatural (Classic Battlestar Galactica Vol. 3 #1).
In range of its egress is a singular planet around which a thickly-ringed graveyard of ships orbits, its survivors making landfall on the planet only to be hunted down by the Meclons—former Cylons who were also inexorably drawn into the singularity (Classic Battlestar Galactica Vol. 3 #1 — #3).
The singularity is one-directional by design as the realm is a trap for Iblis' sworn enemy, the Seraphs (Classic Battlestar Galactica Vol. 3 #3 and #4). It takes the destruction of a Ship of Lights to open a return path that bridges the two universes, thus allowing The Fleet, Lucifer's Cylons, various hapless victims, and the surviving Seraphs to return to the primary universe (Classic Battlestar Galactica Vol. 3 #5).