This year marked the 45th year of Nikon's Small World microscope photography competition, called the Photomicrography Competition, and the winners have just been announced. In order to be valid for entry, photographs must be taken using a light microscope. The subjects of the competition entries range from animal embryos to cells to plants, but they all have one thing in common: these are not things we can see with the naked eye. And they are absolutely beautiful. Here are the top twenty photos from the competition, in order. Enjoy.