Dark Sentinel Crystal
Dark Sentinel Crystals are Utility Crystals of Luminoth design used to monitor key areas. The original Sentinel Crystals were incredibly durable, but many were destroyed due to Dark Aether's toxic atmosphere and constant Ing attack. The improved Dark Sentinel Crystals are sheathed in dark energy, making them more resistant to the toxins of Dark Aether. They still broadcast to U-Mos, who uses the information to keep a watchful eye in Ing activity.
- "During the war, the Luminoth used the Sentinel Crystals to monitor key areas and installations. They are incredibly durable, resisting all but the most powerful of Ing attacks. U-Mos still uses the remaining Sentinel Crystals to keep a watch for Ing activity." —Logbook Data (Metroid Prime 2: Echoes)
- "The original Sentinel Crystals were durable, but they had their limits. The toxic nature of Dark Aether, coupled with constant attack from the Ing, destroyed many of them. The Luminoth responded with the Dark Sentinel Crystal. Sheathed in dark energy, it is more resistant to the atmosphere of the Ing homeworld - and the attacks of its denizens." — Logbook "Dark Sentinel Crystal" (Metroid Prime 2: Echoes)