Human, animals and plants are living things.They vary in size and can be seen with naked eyes.However, there are tiny living things that can only be seen through a microscope.These are called microorganisms.
There are different types of microorganisms.They are bacteria, protozoa,fungi and virus.
Bacteria exist in different shapes, sizes and colours.
Most protozoa are found mainly in ponds, lakes and rivers. Some of them eat other microorganisms as food.
Fungi can be found on mouldy bread, rotten food, trees and forest floors.
Virus is the tiniest microorganism.It can be found living in some bacteria, fungi, protozoa, animals,plants and hunmans
For more information, please visit:http://library.thinkquest.org/CR0212089/micr.htm