|If you squint, you can see Eurasia and Africa?|
The story in this book hinges on the mitochondria within our cells, and a fictional organism even smaller than that called farandolae living inside the mitochondria. The point is to each of these living organisms, the organism it lives inside of is as big as the world is to us. Worlds within worlds, like nesting dolls, and possibly infinite. Who's to say there aren't so many levels of things bigger than us that we may be microscopic to something, somewhere out there.
Size, like everything else in reality, is relative. It's also important to remember that something so tiny, and organism within an organism within cells, is still vitally important.