Subterranean Facilities/The Lava Tubes

-The Reliquary (discussed in the Xenotechnological Incident ) and the front line defenses of the 508 indicate that the Lava Tube network in Asterion's subterranean reaches is likely to hold additional locations with evidence of Cinquefoil presence. 

 -The subterranean Null Singularity bears hallmarks of Cinquefoil Construction