hidden vault symbol, Borderlands 2, secret location, Easter egg, Claptrap's secret stash, hidden room, secret chest, rare loot, unique weapon, hidden Echo recorder, secret boss, mysterious lever, puzzle, secret mission, hidden challenge, concealed area, secret passage, intricate environment details, hidden claptrap dance, secret dialogue, interactive object, hidden reference, pop culture, hidden achievement, detailed textures, game secrets, exploration, hidden Easter eggs, vibrant colors, dynamic lighting, first-person perspective, immersive gameplay experience.