There are millions of living things on Earth, but did you know some of them are practically invisible because they're so tiny? Microorganisms are living things that only have one cell--like bacteria, archaea, and yeast. Readers will learn about the microorganisms they share our planet with, including tiny plants, animals, tardigrades, underwater creatures, soil, and parasites. These creatures come to life in this book through eye-catching illustrations, age-appropriate text, and helpful diagrams. Readers will be able to further their science curriculum learning from outside of the classroom with this volume!