Abstract humanoid figures formed from metal that can move as if liquid

Metal elementals appear to be somewhat abstract humanoid figures formed from metal. They are able to move as if liquid, though they are cool and hard to the touch. Their semi-liquid form permits them to form their extremities into wickedly sharp blades, which is their preferred means of attack. Those wearing metal armor receive no protection against a metal elemental (except for magical bonuses, if any); indeed, on a successful hit one deals an additional 1d8 points of damage to creatures, vehicles, or structures that are made of or in direct contact with some form of metal. Lightning attacks deal double damage to a metal elemental. Like an earth elemental, a metal elemental cannot cross a body of water greater than its own height.