The double compound eyes of a male St. Mark's fly (Bibio marci), submitted by Dr. David Maitland from Feltwell, UK. (Dr. David Maitland)

“In anatomy, heterochromia refers to a difference in coloration, usually of the iris (but also of hair or skin). Although infrequently seen in humans, complete heterochromia is more frequently observed in other species, where it almost always involves one blue eye”. – Wikipedia (Photo by StooMathiesen)

Athletes from Australia's Olympic team going to the 2016 Olympics in Rio present their uniforms alongside Brazilian Samba dancer Sashya Jay at an official unveiling ceremony at Sydney's Bondi Beach, March 30, 2016. (Photo by Jason Reed/Reuters)

A damaged vehicle is seen next to the ring road, around Skopje, near the village of Stajkovci, Skopje, The Former Yugoslav Republic of Macedonia, 08 August 2016. At least 21 people have died and more than 100 are injured in the heavy rain storm that hit the Macedonian capital Skopje late Saturday night causing severe damage to the roads and house infrastructure. More than 80 vehicles were hit by landslides at Skopje's ring road. The highway remains closed. The government announced a 15-day state of emergency in the Skopje and Tetovo region. (Photo by Georgi Licovski/EPA)

In this September 9, 2018 photo, a diver holds onto his catch of lobsters during a fishing journey in the Miskito coast near Cay Savannah, Honduras. A diver makes 75 lempiras ($3) per pound of lobster. An average 10-pound daily haul of lobster is a windfall for people in one of the most impoverished regions of the Americas, so many take the risk, and many suffer for it. (Photo by Rodrigo Abd/AP Photo)

The “EMIEW3” robot (R) demonstrates communicating with a visitor during a press preview in Tokyo on April 8, 2016. Japanese electronics giant Hitachi unveiled its humanoid customer service and guidance robot “EMIEW3” and “remote brain” robotics IT platform. (Photo by Toshifumi Kitamura/AFP Photo)

U.S. Army soldiers with the 1st Battalion, 501st Infantry Regiment deployed to Combat Outpost Sabari, Afghanistan scan their area as they begin a multi-day air assault mission near the Pakistani border of eastern Afghanistan's Khost province May 2, 2012. (Photo by Staff Sgt. Joshua L. DeMotts/U.S. Air Force)

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)