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.

Polish police in riot gear detain protesters, angry over new restrictions aimed at fighting the coronavirus pandemic, in Warsaw, Poland, Saturday, October 24, 2020. The protesters included entrepreneurs, far-right politicians, football fans and vaccine opponents. The clashes come amid rising social tensions and as new restrictions just short of a full lockdown took effect Saturday. (Photo by Czarek Sokolowski/AP Photo)

An ostrich is seen at Woburn Safari park before its opening as coronavirus disease (COVID-19) restrictions begin to ease, in Woburn, Britain on April 11, 2021. (Photo by Andrew Boyers/Reuters)

Visitors look at photographs in the exhibition “Lisette Model Street Life e Horst P. Horst Syle and Glamour” at the art gallery “Camera – Centro Italiano per la fotografia” in Turin, Italy, 27 April 2021. Culture venues reopened to the public as several Italian region are back to COVID-19 yellow zone in the country's tier system. (Photo by Alessandro di Marco/EPA/EFE)

A young woman poses for a selfie at Red Square which is under preparations for the Victory Parade during sunset in Moscow, Russia, Monday, April 26, 2021. Russia will celebrate celebrate 76 years of the victory in WWII on May 9, 2021. (Photo by Alexander Zemlianichenko/AP Photo)

Students protest in red underwear on the Plein in The Hague, The Netherlands, 02 June 2021. The action is part of the #NietMijnSchuld campaign by Dutch union FNV Young & United and the National Student Union LSVb, which are campaigning for a debt-free basic grant. (Photo by Bart Maat/EPA/EFE)

TCU Horned Frogs twirler performs at halftime of the game against the Baylor Bears at Amon G. Carter Stadium in Fort Worth, Texas, USA on November 6, 2021. (Photo by Kevin Jairaj/USA TODAY Sports)

Devotees wearing protective masks pray at a temple in Bangkok, Thailand, 19 June 2020. Thailand opened most businesses to enter the fourth phase of easing coronavirus restrictions after the number of coronavirus cases remains low. (Photo by Diego Azubel/EPA/EFE/Rex Features/Shutterstock)