Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)

Two women look at a mobile phone as they stand on Tiananmen Square during a sand storm in heavily polluted weather in Beijing on February 28, 2013. Beijing residents were urged to stay indoors as pollution levels soared before a sandstorm brought further misery to China's capital. (Photo by Ed Jones/AFP Photo)

Chihuahua Cooper Babb is dressed in a costume at the 7th annual Running of the Chihuahuas event on May 3, 2014, at the First Tennessee Pavilion in Chattanooga, Tenn. (Photo by Doug Strickland/AP Photo/Chattanooga Times Free Press)

A huge colony of Pacific Walrus on Arakamchechen Island in the Northern Bering Sea. (Photo by Francois Gohier/Ardea/Caters News)

These are the dunes of the Namib Desert, taken by Korea's Kompstat-2 satellite. The blue and white area is the dried riverbed of the Tsauchab river. (Photo by The European Space Agency)

TV personality Kylie Jenner attends the 2014 MTV Video Music Awards at The Forum on August 24, 2014 in Inglewood, California. (Photo by Steve Granitz/WireImage)

A model presents a creation from the Jeremy Scott Spring/Summer 2015 collection during New York Fashion Week September 10, 2014. (Photo by Lucas Jackson/Reuters)

Visitors look on as a man (front) inserts two live snakes through his nose and mouth during a performance at an amusement park to celebrate the 65th anniversary of the founding of the People's Republic of China and the 7-day national day holiday, in Jinhua, Zhejiang province October 1, 2014. (Photo by Reuters/Stringer)