Two brave contestants take part in the World Gravy Wrestling Championships at the Rose 'n Bowl in Stacksteads, Lancashire, England on August 27 2018. Contestants must wrestle in the gravy for 2 minutes, points are scored for fancy dress, comedy effect, entertainment and wrestling ability. The event is held to raise funds for the East Lancashire Hospice and competitors nominated charities. (Photo by The Mercury Press)

An artwork called “McJesus”, which was sculpted by Finnish artist Jani Leinonen and depicts a crucified Ronald McDonald, is seen on display as part of the Haifa museum's “Sacred Goods” exhibit, in Haifa, Israel, Monday, January 14, 2019. Hundreds of Christians calling for the sculpture's removal protested at the museum last week. (Photo by Oded Balilty/AP Photo)

This Saturday, July 22, 2017 photo released by Tokyo Zoological Park Society, shows a giant panda cub at Ueno Zoo in Tokyo. The baby panda, born in June, got a check up on Saturday. (Photo by Tokyo Zoological Park Society via AP Photo)

Attendees wear a cardboard “Facebox” at the 2017 South By Southwest (SXSW) Interactive Festival at the Austin Convention Center in Austin, Texas, U.S., on Monday, March 13, 2017. The SXSW Interactive Festival features a variety of tracks that allow attendees to explore what's next in the worlds of entertainment, culture, and technology. (Photo by David Paul Morris/Bloomberg)

Long-tailed mayflies (Palingenia longicauda) at Tisza river near Tiszainoka 135km (84 miles) southeast of Budapest, June 23, 2013. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)