Van cats, relatively large, have a chalky white coat, sometimes with ruddy coloration on the head and hindquarters, and have blue or amber eyes or have heterochromia, are seen at “Cat Villa”, established to protect the cats in Van, Turkey on January 20, 2021. Internationally valid “health certificate” is prepared for Van cats, visited by local and foreign tourists, within a project to protect their generations and increasing their numbers. Health certificates with information such as name, breed, gender, eye color, date of birth, tail feature, color, hearing status and identity are given to people who want to adopt cats. (Photo by Mesut Varol/Anadolu Agency via Getty Images)

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)

“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)

A Sphynx cat at the 2017 Grand Prix Royal Canin international cat show at the Crocus Expo Exhibition Centre in Moscow, Russia on December 2, 2017. (Photo by Sergei Savostyanov/TASS/Barcroft Images)

A curious cat ipeeks out of a bag carried by its owner on a tour of the Cat Expo 2022 in Kuala Lumpur, Malaysia, 30 September 2022. The “Ekspo Kucing”, described as Malaysia's Largest Cat Expo runs from 30 September to 02 October 2022 at the Matrade Exhibition and Convention Centre (MECC) in Kuala Lumpur and “will also feature other variety of pets such as rabbits, hamsters, guinea pigs, reptiles and exotic animals”, the MECC said on its website, along with other highlight events such as a Federation Internationale Feline (FIFe) Cat Competition, Cat Adoptions or a “Sugar Glinder Contest”. (Photo by Fazry Ismail/EPA/EFE/Rex Features/Shutterstock)

Van cat walks in the snow in Yuzuncu Yil University's “cat villa” where they are carefully cared, in Van, Turkiye on January 21, 2022. One of the most important symbols of Van province of Turkiye endangered Van cats are taken under protection at the Van Cat Research and Application Center of Yuzuncu Yil University. They have been the subject of many scientific studies with their unique characteristics. Efforts are continuing to protect the extinction of the Van cat, which is known for its sensuality, friendliness, white silky fur, lion's walk, fluffy tail, different eye colors and fondness for water. (Photo by Ozkan Bilgin/Anadolu Agency via Getty Images)

A child plays with a cat next to a makeshift animal shelter at Cihangir neighbourhood in Istanbul, Turkey, Thursday, March 23, 2023. Turan comes every single day with cat food in his hand to the makeshift shelter he helped build with the other volunteers in the area and takes care of the needs of the cats that reside their every single day. (Photo by Francisco Seco/AP Photo)