A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)

Giant panda Meng Meng plays on a tree at a Siberian tiger-breeding base in Changchun, China on December 10, 2015. (Photo by Xu Chang/Xinhua Press/Corbis)

Solo, a rare baby tapir, makes his debut at Chester zoo, UK on July 18, 2016. The Malayan tapir is an endangered species and Solo is the first ever calf born at the zoo. (Photo by Chester Zoo/Rex Features/Shutterstock)

A baby dives as his mother holds on tightly during a water baby class in Odessa, Ukraine on August 6, 2016. (Photo by Andrey Nekrasov/Barcroft Images)

Visitors pose for pictures under blooming cherry blossoms at a botanical garden in Nanjing, capital of China’s eastern Jiangsu province on March 15, 2019. (Photo by Reuters/China Stringer Network)

A staff member demonstrates how she puts on the helmet of a mock space suit at the C-Space Project Mars simulation base in the Gobi Desert outside Jinchang, Gansu Province, China, April 17, 2019. The facility – comprising several interconnected modules including a greenhouse and a mock decompression chamber – opened its doors to the public. (Photo by Thomas Peter/Reuters)

Russian woman takes selfie near military vehicle during the rehearsal for a military parade in Moscow, Russia, 29 April 2019. Russia will hold a Victory Day military parade on 09 May 2019 to mark the 74th anniversary since the capitulation of Nazi Germany in 1945. (Photo by Yuri Kochetkov/EPA/EFE)

A Sotheby's employee poses with a claw-set diamond ring weighing 36.57 carats during a press preview of an upcoming auction from Sotheby's in Geneva, Switzerland, 08 May 2019. The ring is expected to reach between 4,500,000 to 5,500,000 US Dollars during the “Magnificent Jewels and Noble Jewels” auction on May 14 in Geneva. (Photo by Valentin Flauraud/EPA/EFE)