At first glance, this small brass object looks like some kind of lock, mechanical switch, or forgotten workshop tool. Its real purpose is much more surprising. It is an antique scarificator, a medical instrument once used during the practice of bloodletting. Scarificators became especially common during the 18th and 19th centuries, when doctors believed removing blood could help treat numerous illnesses.

Hidden inside the brass case were several tiny steel blades. The curved lever on top was used to prepare the spring-loaded mechanism. Once the device was placed against a patient’s skin, pressing the trigger caused the blades to emerge rapidly and make several shallow cuts at the same time. Some surviving examples contained 10, 12, 16, or even more lancets.

Doctors could then allow blood to flow naturally or place a heated cupping glass over the cuts. As the glass cooled, the resulting vacuum helped draw additional blood from the area. At the time, bloodletting was based partly on the old belief that illnesses could result from an imbalance of bodily “humours.”

As medical science advanced, bloodletting gradually fell out of favor and tools like this disappeared from everyday medicine. Today, scarificators are mostly found in museums, antique collections, and occasionally flea markets.

So that mysterious little brass box isn’t an ordinary household gadget at all.

It’s a piece of medical history—and one you definitely wouldn’t want demonstrated on you.