Kurdish pesh merga troops fire at Islamic State positions as they move toward the Iraqi town of Badana Pichwk on Monday morning, October 17, 2016. Kurdish forces began Monday advancing on a string of villages east of Mosul, the start of a long-awaited campaign to reclaim Iraq's second-largest city from the Islamic State, which seized it more than two years ago, officials said. (Photo by Bryan Denton/The New York Times)

The world's biggest copy of the Mona Lisa is unveiled on October 28, 2009 in Wrexham, Wales The giant version of Leonardo da Vinci's masterpiece measures 17.5 metres across and is 50 times bigger than the original painting and was created by community groups in Wrexham and artist Katy Webster. (Photo by Christopher Furlong/Getty Images)

Bob Woodward looks at the reconstruction he built of the Orpheus Pavement at Prinknash Abbey on March 31, 2010 in Gloucester, England. The replica mosiac, made of more than one-and-a-half million pieces of stone is described as one of the most significant archaeological projects of recent times. (Photo by Matt Cardy/Getty Images)

Children play marbles on the dirt in Garut, West Java, Indonesia on October 17, 2025. This traditional game, which was popular in the 1980s, is now rarely played by children due to the increasing popularity of modern games with advanced technology. According to a survey by the Indonesian Child Protection Commission (KPAI), more than 71.3% of school-age children own gadgets and play them for a considerable amount of time each day, and as many as 79% of child respondents are allowed to play gadgets for purposes other than learning. (Photo by Algi Febri Sugita/ZUMA Press Wire/Rex Features/Shutterstock)

Members of the Michiana Rocketry prep a 10-foot, 450 pound porta-potty, mounted on rocket motors for launching, Saturday, December 6, 2014, from a field in Three Oaks, Mich. It made an arc and almost landed on a spectator’s pickup truck, 2,000 feet away. A group of Michiana Rocketry club members planned the project for more than two years. The club is trying to increase awareness of rocketry as a hobby and prove it’s possible to turn a porta-potty into a rocket and launch it successfully. About 30 people worked on the rocket, from engineers to sales people who lined up sponsors. (Photo by Don Campbell/AP Photo/The Herald-Palladium)

Few things are more beautiful than puffy white clouds floating in the bright blue sky. Do you remember the time when you would lay on the soft green grass, look up at the sky, and try to recognize shapes in the clouds floating overhead? Wasn’t it wonderful, just lying there, letting the wind caress your skin, as you imagine that the clouds in the sky are actually mystical or not-so-mystical creatures? Dragons, ducks, teddy bears, dinosaurs, everything was up there. It was good old times. As adults we forget about simple pleasures of life. However, an Argentinian artist Martin Feijoo didn’t forget those times, and took them a step further. After imagining what a particular cloud looks like, he draws that particular shape over the picture of the cloud, allowing the entire world to see what goes on in his mind. (Photo by Martin Feijoo)

A newly born female White Rhino runs alongside her mother in Ramat Gan Safari Park near Tel Aviv, Israel, on September 3, 2014. She was born three weeks ago, after more than twenty years without a female White Rhino birth in the Safari, Sagit Horowitz, the safari spokeswoman said. (Photo by Ariel Schalit/AP Photo)

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Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of the East African Rift. The lake is fed by the Southern Ewaso Ng'iro River and also by mineral-rich hot springs. It is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving concentrations of salt and other minerals, notably sodium carbonate (natron).