Did you know that cornflakes contain metallic iron, in finely powdered form, as a dietary supplement. It's only 2.4 mg per serving but...

So strong are neodymium magnets that if you float cornflakes on a bowl of water they can be steered about by the attraction of the magnet. It works best with the ones in the middle: those near the sides probably have some surface tension forces on them as well.

If you don't believe me try it. Steering cornflakes is the best feeling.