I loved the movie Super 8 but there is one thing I've always kind of wondered about and never really come up with a good answer to. When the space ship is gathering all the metal so it can restructure itself, it starts to pull Joe's necklace from his mom up and he holds onto it for a while but in the end lets it go. I could be mistaken, but I always had the impression that this last piece is what finally allows the ship to take off.
Was the necklace literally needed for the ship to be complete? And if so why? And if not, then it must've had some symbolic meaning.