They are quite numerous, and occur just about everywhere on the planet, having even been found in radioactive waste. Scientists estimate that, should you combine all the bacteria on earth, their total mass would be greater than the mass of all the plants and animals put together.
And yet, you can not see bacteria with the naked eye. You will even battle to see one with a decent microscope. Most bacteria have not been classified, and those that have were generally classified because they made people sick.
However, some bacteria exhibit rather interesting characteristics. One such interesting bacteria is the Magnetospirillium Magneticum. This particular chap has the ability to consume iron and turn it into magnetite, which is the most magnetic of all naturally occurring minerals on earth. The bacteria then stores this magnetite and uses it align itself with the earth's magnetic field, which it uses as a navigation system.
Additionally, by using this magnetic nature, a 16-year old Montreal school boy was able to generate around half the voltage of a AA battery from one fifth of an ounce of the bacteria.
Not exactly an answer to the world's power problems yet, but considering how much bacteria there is in the world, he might be on to something.
