Only after World War II did the secret spill: Ōkunoshima, located in the Inland Sea of Japan between Hiroshima and Shikoku, was the top-secret site for manufacturing chemical warfare. When the factories were closed down, a number of exotic wild rabbits were seen freely roaming the island. They were assumed to have been the test subjects for the chemical weapons, which the military failed to eradicate when the factory was demolished.

An army cadet contestant with his kart trailing smoke hits the ramp hard and crashes during the 70 year anniversary soap box derby on April 02, 2023 in Hunstanton, England. Over 40 home built karts raced through the streets of the Norfolk town, around bends and over jumps. The race was first held in1953. (Photo by Martin Pope/Getty Images)

Children in a Hong Kong refugee resettlement area watch as former Vice President Richard Nixon shows them his badminton service. Nixon visited Hong Kong, April 4, 1964, during his tour of countries in the Far East. (Photo by AP Photo)

Soldier boys at Fort Dix, N.J., learn something about guns during their working hours, as they show their girlfriends at a camp dance, December 13, 1940. In front row, playing with the coin amusement gun, from left: Pvt. Tom D'Amato of West Orange; Rose Sinkewicz, behind gun site, of Trenton; Julia Ivans of Trenton, and Pvt. Vernon Landers of Kearney. Back row: Pvts. William Sargent and William Corlies of Philadelphia. (Photo by AP Photo)

A Thai visitor appears to be frightened by a life-size Velociraptor model also known as Raptor at the Dinosaur Planet theme park in Bangkok, Thailand, 25 March 2016. The 500 million baht (14 million US dollars or 12 million euro) theme park opening in the Thai capital aimed to attract more than 15,000 visitors a day featuring a chance to experience more than 200 dinosaurs from various species that are brought back to life. (Photo by Rungroj Yongrit/EPA)

Hindu devotees (not pictured) touch a child with their feet as part of a ritual to bless him during a religious procession held to mark the Gajan festival in Kolkata, India, April 13, 2018. (Photo by Rupak De Chowdhuri/Reuters)

Ukrainian artillery fires towards the frontline during heavy fighting amid Russia's attack on Ukraine, near Bakhmut, Ukraine on April 13, 2023. (Photo by Kai Pfaffenbach/Reuters)

A little girl seen waiting in a queue to participate in the Kumari Puja ritual in Kolkata, India on March 30, 2023. Kumari Puja is an Indian Hindu Tradition mainly celebrated during the Durga Puja / Basanti Puja / Navratri according to Hindu calendar. Kumari actually describes a young virgin girl from the age 1 to 16 who is getting worshipped during the transition of Ashtami / Navami tithi of Durga Puja / Navaratri according to Hindu mythology. (Photo by Avishek Das/SOPA Images/Rex Features/Shutterstock)