The one that if you had it active with one of the audio logs picked up those four boxes would always spawn loot midgets. My friends and I are playing through UVHM and I was just thinking about how that might work for finding Legendary Loot Midgets. We managed to find one in the Tundra Express. Dropped the Bone of the Ancients and now I'm all interested in finding all the other stuff as well.
That is exactly what everyone is doing to find pearls :) Ive found quite a few myself, and I know many other users have found plenty more!
Good thinking, go find some loot :P
Btw, a couple tips if you plan on farming the boxes:
Do not progress story to find bloodwings bloody feathers as it will unlock the doors containing the animals, making your job a little bit harder. Less mobs, quicker runs. If you have the "Creature Slaughter Dome" Dlc, and can access the "Natural Selection Annex", you should start there, a lot quicker :P Also, don't pick up the quest items for "Doctor's Orders" as their placement has a direct correlation to the LLMs spawning in the boxes.
Good luck :)
Assistant Manager at Foveroula and Acid's Pawn Shop I remember Alvor every time I make Skyforge Steel