Tardigrades, which are usually less than 1 mm long, can be found in almost every habitat on Earth, and there are 150 known species found in the ocean. Tardigrades are most famous for being able to survive in extreme environments such as extremely hot (304 °F!) or extremely cold (-328 °F!) temperatures, X-ray radiation a thousand times the lethal dose, and even in the vacuum of outer space! This image of a marine tardigrade (or "water bear"), taken at 40x zoom, was named an Image of Distinction in the Nikon Small World 2013 photomicrography competition.