 FACT: The "Zit" cream that is given to Alex Rider allegedly will  burn through any metal, but is harmless to a persons skin. When  trapped in the aquarium with the giant Man of War jellyfish he uses  the cream against the metal supports of the aquarium. This is  impossible, as salt water aquariums can have no metal in them, as  metal can drastically change the PH balance of the aquarium, and  kill any creature in it.