Siriacus was one of the three Space Pirate Vessels to escape the destruction of their base on Zebes, the others being Orpheon and Vol Paragom. It is not seen in any of the games, but is mentioned in a Pirate Data entry entitled Fall of Zebes recorded on Frigate Orpheon.
- "Zebes has fallen. All ground personnel are presumed dead, either killed by the Hunter clad in metal or in the subsequent destruction of the underground facilities. Our research frigates Orpheon, Siriacus and Vol Paragom were in orbit at zero hour and managed to retreat. Frigate Orpheon is now docked at Vortex Outpost. Orpheon's cargo appears to have a 100% survival rate; Metroids are healthy but on restricted feeding schedules due to uncertain supply status. We are ready to begin research on the Metroids and other promising life-forms. Security status remains at Code Blue; no signs of pursuit from the Hunter." —Pirate Data "Fall of Zebes" (Metroid Prime)