These adorable cats – which are twins – showcase their contrasting blue and green eyes. The cats have a condition called heterochromia iridis, which causes each eye to vary in color. (Photo by @sis.twins/Caters News Agency)

In this photo taken on January 20, 2024 a tourist poses in front of incense sticks drying in a courtyard in the village of Quang Phu Cau on the outskirts of Hanoi. Families living and working in the “incense village” of Quang Phu Cau now also make sticks in yellow, blue and green, catering to visitors eager to snap shots for Instagram. (Photo by Nhac Nguyen/AFP Photo)

A Australian green tree frog wearing a small turtle as a hat, keeping its head dry during its swim in Padang West Sumatra, Indonesia in May 2023. The Australian green tree frog grows up to 11 centimetres tall, the males being smaller that the females. They can live to the age of 25 and their colour alters between green, brown and blue depending on their mood. (Photo by Yan Hidayat/Media Drum Images)

A blue crab, a highly invasive alien species, is seen at Lio Piccolo during the reforestation day on April 05, 2025 in Venice, Italy. The island of Lio Piccolo in the northern lagoon of Venice is being replanted with 16,000 new trees that will protect the salt marsh ecosystem that is fundamental to the natural health of Venice and the lagoon by WOWnature project, an Etifor initiative. (Photo by Simone Padovani/Getty Images)

These Animal Cling Rings are by Japanese artist Jiro Miura, working under brand name Count Blue. Miura creates these exquisitely detailed animal rings as well as figurines; his designs have also been used to create mass produced phone plugs and rings. It's a lucky artist who sees his work become so popular.

A little blue penguin which was found at Papamoa Beach, covered in oil after the Liberian cargo ship, Rena, hit a reef, on October 7, 2011, in Tauranga, New Zealand. Reports of an oil sheen have been spotted on the surface of the water surrounding the ship and two penguins have been found covered in oil. (Photo by SUNLIVE New Zealand/Getty Images)

A student attending a winter military camp reacts during a training session in Ansan, south of Seoul January 3, 2013. Hundreds of students between 11 and 17 years old attend winter boot camp training courses every year. The winter courses range from 4 to 14 days at the Blue Dragon Camp run by retired marines, which also offers summer boot camp for students. (Photo by Kim Hong-Ji/Reuters)