I have just been watching the german television show "Gallileo". They explained how magnets work and they said that there are magnets that are strong enough to magnetize the watermolecules of creatures.
»The molecular magnetism is very weak (millions times weaker than ferromagnetism) and usually remains unnoticed in everyday life, thereby producing the wrong impression that materials around us are mainly nonmagnetic. But they are all magnetic. It is just that magnetic fields required to levitate all these "nonmagnetic" materials have to be approximately 100 times larger than for the case of, say, superconductors.«
Look: It's a levitating frog!