"Hm?" Robin looks curious, sounding amused as Phalanx reaches for his vial, "These? Have you never...?"

But he stops himself mid-sentence, because whether or not Phalanx has, he doubts that enough of them would remember coherently enough to give him a sensible answer. He holds the chain out a little further away. "No, it's mostly chemicals. Bioluminescence. Fungal bacteria reacting to other liquids."

And then, with a clever smile, "If I let you hold it, are you going to give it back?"