In the fairy tale, Sleeping Beauty went to sleep for 100 years in a castle protected by giant thorns and then was revived by the kiss of a prince. In 2000, scientists told a microbial version of this fairy tale, announcing that they had revived bacteria that had lain in suspended animation for 250 million years, encased in salt crystals deep in the Earth.

The name "microbe" suggests creatures that are so tiny you need a microscope to see them. For most microbes this is true, but there are some gargantuan microbes that we can actually see with the unaided eye. On this page, you’ll read about the biggest of the big in each of the main categories of microbes: viruses, bacteria, protists, fungi and, as an extra added bonus, parasitic worms.