Two hippopotamus are fed with pumpkins at the Hanoi Zoo, in Hanoi, Vietnam, 25 October 2018. The zoo has been the home for more than 800 animals of over 90 different species, including three hippopotamus, since it was built in 1976. (Photo by Luong Thai Linh/EPA/EFE)

A picture made available on 08 February 2017 shows staff playing with cats inside the Super Very Very Important Cat (VVIC) room at the CATZONIA cat hotel in Damansara, outside Kuala Lumpur, Malaysia, 07 February 2017. (Photo by Fazry Ismail/EPA)

A rabbit fails to clear an obstacle during a bunny hop competition at the Old Town Square in Prague, Czech Republic, Monday, April 14, 2014. (Photo by Petr David Josek/AP Photo)

Olga Gharkova enters a aromatherapy room at the British Banya bathhouse, Saturday, February 15, 2014, in Krasnaya Polyana, Russia, just a few miles away from the ski slopes where athletes are competing for Olympic medals. (Photo by Jae C. Hong/Associated Press)

A woman views the Mummy of Meresamun in the Ashmolean Museum's new exhibition of artifacts from ancient Egypt and Nubia on November 23, 2011 in Oxford, England. The new gallery is displaying for the first time in decades some of the finest Egyptian and Nubian artifacts in the UK. The Egyptian collection opens to the public from November 26, 2011. (Photo by Oli Scarff/Getty Images)

Chinese archaeologists announced the discovery of 110 life-sized terracotta warriors, guarding the tomb of Qin Shi Huang, China's first emperor.

Photo: Archaeologists work on a terracotta warrior in the third excavation of pit one at the Terracotta Warriors and Horses Museum in Xi'an in northwest China's Shaanxi province Saturday, June 9, 2012. (Photo by AP)

In this undated photo provided by LittleFriendsPhoto.com via Six Flags Discovery Kingdom, Kai, a 17-year-old male California sea lion at Six Flags Discovery Kingdom in Valejo, Calif. peers into the lens of photographer Seth Casteel, known for his “Underwater Dogs” photo series. ... (Photo by Seth Casteel/AP Photo/LittleFriendsPhoto.com via Six Flags Discovery Kingdom)