A worker carries a bag of salt after collecting it from a pond at the Maras mines in Cuzco December 3, 2014. Salt has been obtained in Maras since pre-Incan times by evaporating highly salty local subterranean stream water. The water is intricately channelled through constructions, flowing gradually down onto several hundred ancient terraced ponds. From each pond, a local member of the mine cooperative can produce 150 to 200 kilos per month which can be sold in the markets at $0.34 per kilogram, according to miners. (Photo by Enrique Castro-Mendivil/Reuters)

A “jungle nymph” is measured during the annual weight-in ZSL London Zoo on August 21, 2014 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, is recorded and submitted to the Zoological Information Management System. This is combined with animal measurement data collected from over 800 zoos and aquariums in almost 80 countries, from which zoologists can compare information on thousands of endangered species. (Photo by Oli Scarff/Getty Images)

Frander Arroyo, select wings of butterflies at Blue Morpho Butterfly House in Alajuela, Costa Rica, March 10, 2016. According to Arroyo, owner of Blue Morpho Butterfly House, he collects dead butterflies from his garden to mount as handicraft like earrings, necklaces, paintings and rings for export with prices ranging from $12 to $16 a piece. (Photo by Juan Carlos Ulate/Reuters)

In this October 5, 2016 photo a man looks at the work “Not to be Reproduced” by Rene Magritte at the Kunsthalle art gallery in Hamburg, Germany. The exhibition, which runs from Oct. 7, 2016 until Jan. 22, 2017, features more than 150 masterpieces of surrealism from four of the most significant European private collections of the 20th century. (Photo by Daniel Reinhardt/DPA via AP Photo)

In this photograph taken on October 27, 2017 an Afghan woman collects saffron flowers after picking them in a field on the outskirt of Herat For years, Afghanistan has tried to give farmers alternatives such as fruit crops and saffron to wean them away from poppy farming – the lifeblood of the Taliban insurgency. International donors have splurged billions of dollars on counter- narcotics efforts in Afghanistan over the past decade, including efforts to encourage farmers to switch to other cash crops such as saffron. But those efforts have shown little results. (Photo by Hoshang Hashimi/AFP Photo)

A Russian police officer detains a teenager during rally protesting retirement age hikes in St. Petersburg, Russia, Sunday, September 9, 2018. A government plan to increase the age for collecting state pensions brought protests across Russia's 11 time zones on Sunday even though the opposition leader who called them was in jail. Nearly 300 people were reported arrested. (Photo by Roman Pimenov/Interpress photo via AP Photo)

A pro-Russian armed man secures crash site wreckage of the Malaysia Airlines Boeing 777 plane (flight MH17) at the site of the plane crash near the settlement of Grabovo in the Donetsk region November 16, 2014. Local emergency services have begun collecting parts of the wreckage from its crash site in the middle of the conflict zone, Dutch air accident investigators said on Sunday. Dutch inspectors had hoped to collect the parts themselves, following the downing of the flight on July 17 that killed 298 people, two thirds of them Dutch citizens. But they remain concerned about the safety of their staff in the rebel-held conflict zone, and so have decided to work with local services following an initial focus on finding human remains and belongings. (Photo by Antonio Bronic/Reuters)