A member of staff at Morton & Eden holds an extremely rare early Islamic gold coin on Thursday September 12, 2019, which is expected to fetch £1.4m at auction in London. Measuring a 20mm across, about the size of a modern £1 piece, it is one of the world's rarest and most treasured Islamic gold coins from the first dynasty of Islam, the Umayyad gold dinar dated 105h (723AD). (Photo by Victoria Jones/PA Images via Getty Images)

U.S. President Donald Trump gestures during his visit to a section of the U.S.-Mexico border wall in Otay Mesa, California, U.S. September 18, 2019. Trump threatened to do “dastardly things” to Iran in response to the drone attacks on the world’s largest oil plant in Saudi Arabia. The US President indicated he is wary of involving America in another war in the Middle East – but he did not rule out a military attack. (Photo by Tom Brenner/Reuters)

A camel calf is seen among a herd in the desert near Dakhla in Morocco-administered Western Sahara, on October 13, 2019. In the Oued Eddahab desert in Western Sahara, Habiboullah Dlimi raises dairy and racing camels just like his ancestors used to, but with a little help from modern technology. While his animals roam free and are milked traditionally, by hand, at dawn and dusk, they are watched over by hired herders and Dlimi follows GPS coordinates across the desert in a 4X4 vehicle to reach them. (Photo by Fadel Senna/AFP Photo)

A Maori warrior prepares to challenge Prince Charles during his welcome to Takanhanga Marae in Kaikoura, New Zealand November 23, 2019. (Photo by Tracey Nearmy/Reuters)

A palomino horse's mane is seen against the sky at Spancil Hill horse fair in Spancil Hill, Ireland June 23, 2018. (Photo by Clodagh Kilcoyne/Reuters)

A woman is dragged away by Chinese men moments after she was seen talking to journalists near the site of a reported explosion outside the U.S. Embassy in Beijing, China, Thursday, July 26, 2018. A man exploded a small homemade bomb outside the U.S. Embassy in Beijing on Thursday, injuring only himself, according to police and an embassy spokesperson. (Photo by Ng Han Guan/AP Photo)

A chimpanzee looks in the direction of a camera at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates in Gaenserndorf, near Vienna, 17 September 2018. 34 former laboratory chimpanzees of former Austrian pharmaceutical company Immuno AG spend their lives at the Gut Aiderbichl Sanctuary for Traumatized Chimpanzees and other Primates since 2009. (Photo by Christian Bruna/EPA/EFE)

Mini-pigs perform during the presentation in Balashikha, Russia on December 19, 2018. (Photo by Maxim Shemetov/Reuters)