Stray dogs stand on tombs in Diamond Hill cemetery in Hong Kong, China, 04 April 2017. According to the lunar calendar, the Qingming Festival is observed on 04 April . The Qingming Festival, also known as Tomb-Sweeping Day, is marked by Chinese people by going to the cemetery to cleaning up tombs, bring flowers, and making offerings to their ancestors. (Photo by Jerome Favre/EPA)

A man wearing a mouth-nose protection to protect against the coronavirus walks past a department store window with the words “BACK TO LIFE” in Schwerin, Germany, Thursday, April 15, 2021. (Photo by Jens Buettner/dpa via AP Photo)

Pope Francis attends a circus performance during his weekly general audience at Paul VI hall on December 22, 2016 at the Vatican. (Photo by Alberto Pizzoli/AFP Photo)

Russian honor guard soldiers warm up prior a rehearsal for the Victory Day military parade in St. Petersburg, Russia, Wednesday, May 3, 2017. The parade will take place at Dvortsovaya (Palace) Square on May 9, to celebrate 72 years after the victory in WWII. (Photo by Dmitri Lovetsky/AP Photo)

Cottbus Aviation Museum specialists prepare a Soviet Tupolev 134 A passenger plane for dismantlement in Gruenz, Germany, 10 July 2017. The team is preparing the 29 ton plane for transport from a garden in Gruenz to the Aviation Museum in Cottbus. The plane' s owner acquired it in 1991 and transported it with nine tractors and numerous helpers to his vegetable garden where he planned to open a cafe. The plane, formerly used by the East German Stasi for anti- terror operations training, is 30 metres long. (Photo by Jens Büttner/Zentralbild/DPA)

Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)

A Muslim boy takes part in Friday prayers on a street outside a mosque in Mumbai, India, June 24, 2016. (Photo by Shailesh Andrade/Reuters)

People watch a crocodile with a used motorcycle tyre around its neck on a river in Palu, Central Sulawesi province, Indonesia September 20, 2016 in this picture taken by Antara Foto. Residents suspect the tyre was garbage thrown into the river before it became trapped around the crocodile's neck, reported Antara. (Photo by Mohamad Hamzah/Reuters/Antara Foto)