The Scintillans were a species.
In his own distorted memories, Omega recalled that Vandekirian was at least partly responsible for the sabotage of the Eurydice. He had discovered that detonating a star to fuel the Eye of Harmony would jeopardise the existence of the Scintillans. However, Omega continued anyway.
After hearing about the Scintillans from Daland, the Fifth Doctor confronted Omega and revealed that the Scintillans weren't a part of the time experiments, but a memory Omega had taken from the Doctor[statement unclear]. The Scintillans were a species the Doctor accidentally killed when he tried to save some Lurmans. The Doctor believed Omega had subconsciously used this to explain away Vandekirian's betrayal. Sentia (taken over by Vandekirian's personality) attempted to pilot the Eurydice into the anti-matter universe, so Omega would be trapped again. The Doctor and Daland escaped, while Omega was trapped on the ship, as it and Omega were supposedly pulled back into the anti-matter universe. (AUDIO: Omega)