What's Smaller Than a Pygmy Shrew?

A pygmy shrew is small―it's among the littlest mammals! A ladybug is even smaller, but it hardly seems tiny when you compare it to a protozoa! And there are many things smaller still―so small that we can see them only with a microscope. Would you believe there are particles that are so tiny that we can't measure their exact size? Explore the huge world of the very small!