Want to keep your enemies at bay? How about throwing a jar of scorpions at them? Well, that’s exactly what some ancient people did, National Geographic writes:

In the second century, the inhabitants of the fortress city of Hatra—in what is now Iraq—managed to hold off an attacking Roman army by hurling pots full of deadly scorpions onto the legionnaires.

National Geographic even made a real scorpion bomb, then photographed and x-rayed it.

An expert in ancient pottery created an authentic replica of a terracotta pot like those found at the desert fortress of Hatra near modern Mosul, Iraq, where scorpion bombs had successfully repulsed Roman besiegers in AD 198. After some searching, six deadly Iraqi Death Stalker scorpions were obtained from an exotic pet shop. But now, in the National Geographic studio, photographer Cary Wolinsky and his scorpion wranglers found themselves facing the same threat of “blowback” that the defenders of Hatra had somehow overcome. How does one go about stuffing deadly scorpions into a jar without getting stung? In antiquity, there were several techniques for handling scorpions “safely”—none of them all that safe. The National Geographic team hit on a method unavailable to the desert dwellers of Hatra: the wranglers placed the scorpions in a refrigerator to slow them down before each photo shoot.

Making a scorpion bomb was chronicled in the book Greek Fire, Poison Arrows & Scorpion Bombs. The author, Adrienne Mayor, says that the scorpion bomb recipe went over quite well:

Countless parents told me that their twelve-year-old boys (and some girls) loved the recipe for making scorpion bombs, the live “grenades” that had saved the ancient desert city of Hatra from the besieging Roman army of Emperor Septimius Severus in AD 198-99. Visions of homemade spin-offs troubled my conscience, imagining kids gleefully lobbing baby-food jars filled with hapless spiders, wasps, fire ants, etc at school bullies. It turned out that grown-ups were just as devilishly attracted to the notion of re-creating ancient biochemical weapons. I had to remind History Channel TV producers, for instance, to don gas masks when they replicated toxic fumes devised by the ancient Spartans.

So how do you do it? Well, here’s what Mayor says:

In antiquity the common technique was to verrrrrry carefully spit on the business end of the scorpion. But that requires nerves of steel and perfect aim. Resorting to a method unavailable to the ancient desert-dwellers in Iraq, they placed the scorpions in a refrigerator to induce torpor before each photo session. The resulting photograph and X-ray of the replica scorpion bomb of Hatra was a smashing success and one of my favorite souvenirs of this book.

More from Smithsonian.com:

If Syria Uses Chemical Weapons, Here’s How They’ll Work

In the Military, Inventiveness of All Kinds Is a Weapon