Opossums on their mothers back at a game reserve in Central Minnesota, USA, on September 2, 2013. (Photo by Caters News Agency)

Gelada baboons (Theropithecus gelada) play in their enclosure at the Zoo in Zurich, Switzerland, Wednesday, May 15, 2013. (Photo by Steffen Schmidt/Keystone/AP Photo)

A masked Burundian protester faces soldiers in front of a burning barricade during an anti-government demonstration against President Pierre Nkurunziza's bid for a third term in the capital Bujumbura, Burundi, 25 May 2015. Street protests continued on 25 May as the United Nations Secretary-General Ban Ki-moon condemned the killing of the leader of the oppsition party Union for Peace and Development (UPD) Zedi Feruzi who opposed Nkurunziza's bid. (Photo by Dai Kurokawa/EPA)

In this January 7, 2016, photo, conservationists of Borneo Orangutan Survival Foundation hold a baby orangutan rescued along with its mother during a rescue and release operation for orangutans trapped in a swath of jungle in Sungai Mangkutub, Central Kalimantan, Indonesia. Last year's forest fires drove orangutans closer to the river bank, where they had to live in an over-populated swath of forest as thin as 30 meters wide along the river. (Photo by Dita Alangkara/AP Photo)

Green algae sits on a beach in Kuwait City, Kuwait, 28 February 2017. The formation of green algae is a normal phenomenon that occurs every year at the shores of Kuwait. (Photo by Raed Qutena/EPA)

Collided passenger train cars are seen in Taebaek, South Korea, Tuesday, July 22, 2014. Two passenger trains collided head-on in eastern South Korea on Tuesday afternoon, killing one passenger and injuring dozens, fire officials said. (Photo by AFP Photo/Yonhap)

A woman poses for her husband alongside a giant camera Thursday, November 7, 2013 outside the Historic Green County Courthouse in Monroe, Wis. Chicago photographer Dennis Manarchy created what's being called the world's largest camera. It's 35-feet long and 12-feet tall it's a working replica of a vintage accordion-style camera that produces 16- by 24-foot prints, the equivalent of a two-story building. The giant camera is on display in Monroe through November 17 because a Monroe company manufactured the specially-built trailer. Manarchy plans to tow the camera around the country to shoot photos of indigenous cultures. (Photo by Mark Hoffman)

People attend the 49th annual New York City Gay Pride Parade in New York, New York, USA on 24 June 2018. (Photo by Erik Pendzich/Rex Features/Shutterstock)