Which is exactly my point, if barnacles are all on planets rich in arsenic, who's to say its not extracting that arsenic? So what would happen if we dropped some arsenic near the barnacle? The barnacle is almost like a refinery, it takes the raw ore, turns it into something, which the unknown ship then absorbs. These planets may have similar elements that we can salvage by shooting rocks, which is probably much more primitive and time consuming then using barnacles which could absorb bulk minerals and nutrients and then pass it onto the unknown ship, the meta-alloy could just be a waste product from this process. I'll look more into this myself today, nothing else to do at work. What happens if a large amount of the nutrients the barnacle is seeking is dropped near one? Would it absorb those minerals and process it into whatever the unknown ship absorbs? perhaps this is a way to trigger the barnacle becoming "full" and transmitting a signal to the ship for pickup.