Bielefeld University’s Achim Mueller, Tianbo Liu, and their colleagues have made soccerball shaped nanocapsules from molybdenum-containing units. They have found that replacing the iron stitching with lanthanide ions allows them to momentarily open the capsules. Components can then sneak in before the nanoscopic opening snaps shut in a kind of “Close Sesame” as if by some nocturnal Arabian magic.