High-rise buildings are partly covered by heavy fog at Hong Kong's Victoria Harbour Monday, March 20, 2017. Fog blanketing Hong Kong is common in springtime and may greatly affect shipping and aviation. (Photo by Vincent Yu/AP Photo)

Women practice swimming with mermaid tails at AquaMermaid swimming school, a mermaid training school in Chicago, United States on March 19, 2017. Participants are fulfilling their lifelong ambitions of becoming mermaids with a new type of fitness mermaid swimming. (Photo by Bilgin S. Amaz/Anadolu Agency/Getty Images)

Fire fighters, emergency service vehicles and a helicopter in Moskovsky Prospekt at the entrance to Tekhnologichesky Institut station of the St Petersburg metro in the aftermath of an explosion which occurred in a train at 14:40 Moscow timeon April 3, 2017. (Photo by Peter Kovalev/TASS)

A dancer performs before a judging panel during the World Irish Dancing Championships in Dublin, Ireland on April 11, 2017. The April 9-16 event draws some 5,000 performers from Ireland and overseas, including from both the Irish diaspora in places like the United States and Australia as well as less likely countries such as Russia and Japan. (Photo by Clodagh Kilcoyne/Reuters)

A man driving a vintage car reacts as he passes by crabs crossing a highway on their way to spawn in the sea in Playa Giron, Cuba on April 25, 2017. Each year, after the first spring rains, millions of red, yellow and black landcrabs march for days from the surrounding forests to the bay on Cuba's southern coast to spawn in the sea. (Photo by Alexandre Meneghini/Reuters)

Two girls wearing traditional Sevillian dresses talk during the “Feria de Abril” (April Fair) in Sevilla on April 30, 2017. The fair dates back to 1847 when it was originally organized as a livestock fair but has turned into a week of flamenco dancing, music and bullfighting. (Photo by Cristina Quicler/AFP Photo)

An anti-government protester shouts at a police officer in downtown Caracas, Venezuela, Wednesday, May 10, 2017. Opponents of President Nicolas Maduro will attempt to march to the Supreme Court to protest its decision to gut the opposition-controlled congress of its powers, a ruling that was quickly rescinded under a barrage of international criticism but that set off weeks of political unrest that have left some three dozens killed. (Photo by Fernando Llano/AP Photo)

In this photo taken on Saturday, April 29, 2017, a candle is lit in a roadside shrine as the sun sets across a nearby lake of Pineia in the village of Souli, in the Peloponnese region of southern Greece. Made of iron sheeting, stone, wood, concrete or marble, tens of thousands of such shrines punctuate Greece’s roadside scenery, a common sight in a country that has one of the European Union’s worst road fatality rates. (Photo by Petros Giannakouris/AP Photo)