(L-R) Playmates Summer Altice, Monica Sims and Heather Rae Young attend the Playboy party with TAO at Spire Nightclub on February 4, 2017 in Houston, Texas. (Photo by Christopher Polk/Getty Images for Playboy)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

Rwandan refugees cross the Rusumo border to Tanzania from Rwanda carrying their belongings, goats, mattresses and cows, May 30, 1994. The bloodshed that claimed 800,000 Tutsi and moderate Hutu lives began 25 years ago on April 7, 1994, when a plane carrying Rwandan President Juvenal Habyarimana, Burundi President Cyprien Ntaryamira and a French air crew was shot down. (Photo by Jeremiah Kamau/Reuters)

An Alitalia plane approaches to land as starlings fly at Fiumicino international airport in Rome October 14, 2013. Italy will have to notify a planned government-led 500-million-euro bailout of near-bankrupt airline Alitalia to EU regulators who will then assess whether the measure complies with EU state aid rules, the European Commission said on Monday. (Photo by Max Rossi /Reuters)

Kylie Jenner shows off a lot of cleavage in these new photos added to her Snapchat account on Thursday, August 25, 2016. Something that a lot of the 19-year-old reality star's fans pointed out was that her breasts looked larger than normal and she took to Twitter to explain why. Kylie said that she has “never” gotten her breasts done and that they look large because “it's that time of the month”. She even offered to let a fan feel them to prove that they are real! “They will deflate soon. And it will be a sad sad day”, Kylie added. (Photo by Scope Features)

Blankets cover the bodies of a woman (right) and a man (left background) hit by a northbound Penn Central train (background) as they waited with a crowd at Pennsylvania Railroad station in Elizabeth, N.J. on June 8, 1968 to view the southbound train carrying the body of Sen. Robert F. Kennedy to Washington. The woman was identified as Mrs. Antoinette Severini, 54, and the man, John Curia (age unavailable), both of Elizabeth. (Photo by AP Photo)

Five-month-old baby elephant Fah Jam swims during a hydrotherapy treatment as part of a lengthy rehabilitation process to heal her injured front left foot at a rehabilitation center in Pattaya, Thailand January 5, 2017. The baby elephant was injured at three months old when she got stuck in an animal snare put up by villagers to prevent elephant intrusions in Chanthaburi province. (Photo by Athit Perawongmetha/Reuters)

Elizabeth Mills jumps in front of the Conservative Political Action Conference (CPAC) sign at National Harbor, Md., February 23, 2018. (Photo by Joshua Roberts/Reuters)