Camera trapper Xavier Hubert-Brierre put this large mirror on the side of a road through the jungle in Gabon and left a camera there to record how the animals would respond to their own reflections. A silverback gorilla thought it was seeing another silverback and responded by trying to scare off the potential challenger… (Photo by Xavier Hubert-Brierre/Johns Hopkins University Press)

A woman wears false flag eyelashes during the St Patrick's day parade through Dublin city centre on St Patrick's day, on March 17, 2013. (Photo by Julien Behal/PA Wire)

A general view of Stonehenge during the annual Perseid meteor shower in the night sky in Salisbury Plain, southern England August 13, 2013. The Perseid meteor shower is sparked every August when the Earth passes through a stream of space debris left by comet Swift-Tuttle. Picture taken using a long exposure. (Photo by Kieran Doherty/Reuters)

Lisa Yu crawls through a mud pit under low slung barbed wire as she competes in The Tough Bloke Challenge on March 4, 2012 in Melbourne, Australia. The Tough Bloke Challenge is one of the most gruelling adventure runs in Australia consisting of 18 obstacles over a 6 km cross-country course laden with thick mud-pits and ice-cold water crossings. (Photo by Scott Barbour/Getty Images)

A French farmer leads her cow through the livestock area as preparations continue on the eve of the opening of the International Agricultural Show in Paris, France, February 26, 2016. The Paris Farm Show runs from February 27 to March 6, 2016. (Photo by Benoit Tessier/Reuters)

The Blue Man Group performs on stage during a media preview ahead of their show in Singapore on March 31, 2016. Blue Man Group was started by three friends in New York in 1991 as a way to celebrate the human spirit through music, science, art and theater. (Photo by Roslan Rahman/AFP Photo)

A reveller wearing a demon costume takes part in the traditional festival of “Correfoc” in Palma de Mallorca, on January 17, 2015. The Correfoc is a night of revelry in which participants dress as demons and devils, and move through the streets scaring people with fire and fireworks. (Photo by Jaime Reina/AFP Photo)

Ukrainians swim in an ice hole as part of the celebration of the Epiphany in Kiev, Ukraine, Monday, January 19, 2015. Orthodox believers celebrate the holiday of the Epiphany on Jan. 19, and traditionally bathe in holes cut through thick ice on rivers and ponds to cleanse themselves with water deemed holy for the day. (Photo by Sergei Chuzavkov/AP Photo)