Inventions like the microscope and the camera have allowed us to discover parts of the natural world that had remained hidden for the majority of the history of humankind. The Nikon Small World competition, which was founded in 1974, showcases the best examples of photomicrography—images taken under a microscope—from around the world, and year after year they continue to delight and amaze. In 2013, the competition received more than 2,000 entries from 80-plus countries around the world. These images happen at scales so small the recognizable becomes distorted, abstract, and revelatory. Whether it’s a shrimp’s eye, a turtle’s retina, or a mouse’s inner ear, below is a selection of images that details the inner world of animals, their body parts, their inner organs, and the internal structures that allow them to perceive the world and function in it.