Bought this 22-page 'short' for 49p a couple of years back, noticed it's now free.

Viruses are the smallest living things known to science, yet they hold the entire planet in their sway. Rabbits with Horns and Other Astounding Viruses explores the bizarre places viruses dwell, and considers the often unexpected ways they influence our world. From agricultural production and crystal caves to rabbits with horns and cervical cancer, viruses are behind many of the wonders—some fascinating, some frightening—of the natural world, as well as some of our greatest medical challenges. Through his engaging considerations of the tobacco mosaic virus, viruses in ocean algae, and the human papillomavirus, award-winning science writer Carl Zimmer brings us up to speed on the nuances and depth of today's cutting-edge scientific research on virology.