Vicious-looking remnants of spiked metal devices used by the Nazis to tattoo prisoners have joined the Auschwitz Museum collection.

The devices consist of metal plates armed with needles a few millimeters long that fit into a mechanical stamp, thus creating a specific digit. The stamp would be dipped in ink and pressed against the skin. A blow with the inked stamp pushed the needles into the skin, injecting the ink. At first the stamps were administered to the chest, and later to the left forearm.

The original tattoo stamps had been believed to be long-lost and even now, "The finding, collected in the area of the camp evacuation route, is incomplete," Elzbieta Cajzer told the museum.

Tattooed digits are a hallmark of many Holocaust survivors. The Nazi camps, notably Auschwitz, began by marking the clothing of inmates with their specific numbers but found that inefficient as clothing passed from the dead to the living. Auschwitz therefore began the practice of tattooing the inmates' chests and later, their forearms. Some Jews had a triangle added to their tattoo.

In Israel, some members of younger generations have begun having numbers tattooed in gray-blue on their forearms as a mark of respect, and identification with survivors of the Holocaust. Not everybody views this practice positively, however; some call it tasteless and disrespectful.