It would be impossible to say, so to make things easy, biologists have divided them into five big kingdoms. Bacteria is in the Moneran Kingdom. Bacteria are tiny organisms that can only be seen by a very high-powered microscope. Blue green algae from the Archaic Era 3.5 billion year ago was actually a bacteria. There are helpful and harmful bacteria in the world.
Helpful bacteria makes yogurt.
One type of harmful bacteria gives you strep throat. Protists are one celled organisms. Like the bacteria, protists are very tiny and still need a microscope to be seen. Protists evolved about 1.5 billion years ago. The diatom, amoeba and algae are protists.