A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

An instructor (C) adjusts the posture of students of flight attendant major during a training session at Anhui Foreign Languages University, in Hefei, Anhui province, China, May 25, 2015. (Photo by Reuters/China Daily)

Akram Abu al-Foz places a painted empty shell on top of a Christmas tree he decorated from empty shells he collected in the rebel held besieged city of Douma, in the eastern Damascus suburb of Ghouta, Syria December 23, 2016. (Photo by Bassam Khabieh/Reuters)

A green iguana, or American iguana sits on an Aldabra giant tortoise, the largest tortoise of the world, in their enclosure at the zoo park of Lille, northern France, on February 11, 2019. (Photo by Philippe Huguen/AFP Photo)

Young dancers from the Style Dance Academy perform during a Mother's Day block party in Caracas, Venezuela, Sunday, May 19, 2019. Although Mother's Day was officially celebrated the previous weekend, people in the Petare area organized the neighborhood party to celebrate the mothers of their community. (Photo by Rodrigo Abd/AP Photo)

Owners and their dogs take part in “HK Doggie Dash 2018”, an event held to raise money for for abandoned and surrendered dogs in Hong Kong on April 15, 2018. Dozens of pugs and dachshunds compensated for their modest speed with peppy spirits at Hong Kong’s inaugural “doggie dash” on April 15 that raised funds and awareness for the city’s abandoned and rescued dogs. (Photo by Isaac Lawrence/AFP Photo)

Migrants try to board a truck at Ouistreham ferry port in the hope of reaching the UK on September 12, 2018 in Ouistreham, France. After the clamp down at Calais many young migrants are seeking out new routes to the United Kingdom as stowaways on vehicles making the channel crossing by ferry from French ports. The migrants, of mostly African origin, camp out on the roadside and woodland areas as the authorities prevent the setting up of any camps. (Photo by Christopher Furlong/Getty Images)