A worker walks through a salt pan on the eve of May Day or Labour Day on the outskirts of the southern Indian city of Chennai April 30, 2014. India is the third largest salt producing country in the world after China and U.S. with global annual production about 230 million tonnes, according to government data. (Photo by Reuters/Babu)

A person drags a suitcase as a boy clings to it on a square in front of a railway station ahead of the Chinese Lunar New Year in Qingdao, Shandong province, January 28, 2014. About 3.62 billion trips will be made during the 40-day Spring Festival travel rush, which started from January 16, reported Xinhua News Agency citing a government official. (Photo by Reuters/China Daily)

South Korea's Lee Dae-ho is hit by a pitch off Taiwan's pitcher Pan Wei-lun during the second inning of their first round game of the World Baseball Classic at Gocheok Sky Dome in Seoul, South Korea, Thursday, March 9, 2017. (Photo by Ahn Young-joon/AP Photo)

The National Geographic Photo Ark is a travelling exhibition of photographer Joel Sartore’s quest to create a photo archive of biodiversity around the world. So far, Sartore has captured studio portraits of more than 6,000 species – a number that he hopes to double. On 1 July, the ark will open at Melbourne zoo – the first time it has been exhibited in the southern hemisphere. More than 50 portraits will be on display, including many of Australian endangered animals being protected by programs at the zoo itself. These captions have been edited from text supplied by Melbourne zoo. Here: Barking owl. (Photo by Joel Sartore/National Geographic Photo Ark/The Guardian)

A girl covers her face as she is daubed in colours during the religious festival of Holi inside a temple in Nandgaon village, in the state of Uttar Pradesh, India, March 5, 2020. (Photo by Adnan Abidi/Reuters)

A homeless man wearing face masks to protect against coronavirus, waits to receive basic medial help from members of a group of volunteer doctors of the Dom Druzei (Home of Friends) NGO in Moscow, Russia, Wednesday, April 1, 2020. As Moscow goes into lockdown amid the coronavirus pandemic, thousands of homeless people have trouble receiving food, water and shelter as Russia's capital closes non-essential businesses, cafes and parks. (Photo by Pavel Golovkin/AP Photo)

A woman wearing a face mask and a child sit between rail tracks, during the imposition of large-scale social restrictions by the government to prevent the spread of the coronavirus disease (COVID-19) in Jakarta, Indonesia, April 12, 2020. (Photo by Willy Kurniawan/Reuters)

A health worker wearing a protective suit is disinfected inside a portable tent outisee the Gat Andres Bonifacio Memorial Medical Center during an enhanced community quarantine to prevent the spread of the new coronavirus in Manila, Philippines, Monday April 27, 2020. (Photo by Aaron Favila/AP Photo)