Watch: Recent microbial discoveries are changing our view of life on Earth
A closer look at protists highlights how much we don't know about life on our planet
![An image of a microscopic diatom which has a hard porous cell wall on a black background.](jpg/100723_protist_feate707.jpg)
This microscopic diatom, a type of protist, has a hard, porous cell wall.
Dennis Kunkel Microscopy/Science Photo Library/Alamy Stock Photo