A photographer tested the concentration of several pairs of dogs as he captured their reactions to treat time in a series of shots. Christian Vieler, 47, of Waltrop, Germany, has been a professional dog photographer since 2016. He came up with the idea of snapping two dogs catching treats simultaneously. Here: Basset Hounds. (Photo by Vieler Photography/Caters News Agency)

Boys dressed in historical uniforms stand before a military parade in Red Square in Moscow November 7, 2014. The parade marked the anniversary of the 1941 parade when Soviet soldiers marched through the Red Square towards the front lines of World War Two. (Photo by Maxim Shemetov/Reuters)

The “Strandbeest” sculpture created by Dutch artist Theo Jansen walks at Federation Square on February 1, 2012 in Melbourne, Australia. The 12 metre long, 4 metre high and 2 metre wide structure built of plastic tubes and bottles designed to walk using wind energy will be on display at Federation Square until February 26. (Photo by Scott Barbour/Getty Images)

A bulldog dressed as Marilyn Monroe poses for a photograph during the annual Tompkins Square Halloween Dog Parade in the Manhattan borough of New York City, October 24, 2015. (Photo by Stephanie Keith/Reuters)

An injured protestor is led away during clashes with police near Tahrir Square on November 23, 2011 in Cairo, Egypt. Thousands of Egyptians are continuing to occupy Tahrir Square after four days of clashes with security forces despite a promise from military leaders to bring forward Presidential elections. (Photo by Peter Macdiarmid/Getty Images)

In Mumbai, the windows of new high-rise apartment blocks, old low-rise residential buildings and shantytown shacks portray the disparity in living conditions and incomes in the Indian city. Rents for a place to live range from more than $2,000 to less than $5 a month. Here: Windows and doors of an old residential building are pictured in central Mumbai October 10, 2014. The cost for buying a residential apartment in Mumbai close to the city centre ranges from 12,000 Indian rupees ($ 200) per square feet to 112,552 Indian rupees ($ 1800) per square feet. (Photo by Danish Siddiqui/Reuters)

The November 2018 Square Print Sale, presented by Magnum Photos and Aperture, brings together over 100 images to explore perspectives on transition and transformation in photography. Here: New York City, 1965, by Joel Meyerowitz. “A girl on a Vespa on her way to who knows where, when the light stopped her at the 72nd street crossing near the Dakota, where John Lennon would one day cross paths with his fate. She takes this moment to finesse a fingernail before she resumes her downtown journey, while I, stopping at the same crossing, but on foot, leap into the street to capture this vision of a dream girl before time takes her on her way”. (Photo by Joel Meyerowitz/Courtesy Aperture)