Blue is mentioned in ECHO recordings as having been found and befriended by Dahl security officer Elyse Booth, who named the crystalisk after its color. When Overseer Harchek ordered that crystals be harvested from the crystalisks, the results proved fatal to the previously docile beasts and those remaining, with Blue among them, retaliated. Harchek's final recording indicates that it was Blue that killed her personally.
When Marcus Kincaid's safe is dropped into the Caustic Caverns and the Vault Hunters pursue it, the safe eventually lands on Blue, who must be defeated to open the safe.
- Main article: Safe and Sound
- Blue only appears during and after the mission Safe and Sound.
- Characters standing underneath Blue when it is killed will be trapped by its body. Once Blue's legs are buried, they will be able to move freely.
- Killing Blue before any of its leg crystals grow back completes the "Harchek's Revenge" challenge.
- Blue has an increased chance to drop the legendary Fabled Tortoise shield.
- As of Patch 1.2.0, Blue has increased health.