Impressive images of these alien-like creatures were captured underwater – photographer Cai Songda is a keen diver and did not miss the chance to snap pictures of the unique “aliens”. Here: A Tremoctopus Gracilis in the waters around Anilao, Philippines. (Photo by Cai Songda/Caters News Agency)

The Sculpture Bank (2017) by Chinese artist Mu Boyan is exhibited along the Bondi to Tamarama Coastal walk as part of the Sculpture by the Sea exhibition in Sydney, Australia, October 18, 2018. (Photo by Charlotte Curd/The Guardian)

Two hippopotamus are fed with pumpkins at the Hanoi Zoo, in Hanoi, Vietnam, 25 October 2018. The zoo has been the home for more than 800 animals of over 90 different species, including three hippopotamus, since it was built in 1976. (Photo by Luong Thai Linh/EPA/EFE)

These Northern Lights “rainbows” have turned the sky greener than the Earth below. Vitaly Istomin, 26, spent several nights in freezing conditions under the stars in northern Russia’s Khibiny Mountains to capture the aurora’s “rainbows”. (Photo by Vitaly Istomin/Caters News Agency)

On Saturday, September 2, 2017, local Chinese villagers gathered to celebrate a folk festival parade known as “Dog carrying Day” in Jiaobang village, Gedong Town, Jianhe county, Qiandongnan Miao and Dong Autonomous Prefecture, southwest China's Guizhou province. (Photo by Imaginechina/Rex Features/Shutterstock)

Indian passengers travel on a local train in New Delhi, India, October 2017. Constructed in 1975 to bypass the crowded and passenger-heavy Old Delhi, New Delhi and Hazrat Nizamuddin railway stations, the railway line once used to be the lifeline of the capital. (Photo by Ankur Dutta/Barcroft Media)

A tiger yawns next to a piglet at the Sriracha Tiger Zoo, in Chonburi province, Thailand, June 7, 2016. (Photo by Chaiwat Subprasom/Reuters)

A girl looks at other children practicing on a boxing ring during an exercise session at a boxing school, in the Mare favela of Rio de Janeiro, Brazil, June 2, 2016. For many young residents the Luta Pela Paz (Fight For Peace) academy offers a glimpse of an alternative: a chance to build discipline and self-esteem through boxing and martial arts. (Photo by Nacho Doce/Reuters)