Curators at the Auschwitz museum have found a gold ring and necklace inside an enamel mug that is on exhibit at the museum, the BBC reported Wednesday.

The jewelry was discovered during maintenance work on the museum’s collection of enamel kitchenware. It had been concealed beneath the mug’s fake bottom, which gradually eroded over time, according to the British news network.

Many Jews hid valuable items in their luggage when they were deported to Nazi death camps such as Auschwitz.

The Auschwitz-Birkenau State Museum said the jewelry – like other objects accidentally discovered – would be carefully documented and secured, but warned that the likelihood of finding the owners was slim “because there are no traces left on the objects to help identify them”.

The mug in which the jewelry was found is one of 12,000 cups, pots, bowls, kettles and jugs held by the museum. These are items looted by German forces from the luggage of people who arrived at Auschwitz-Birkenau during World War Two.

“It turned out that one of the mugs has a double bottom,” Hanna Kubik of the museum’s Memorial Collections told the BBC. “It was very well hidden; however, due to the passage of time, the materials underwent gradual degradation, and the second bottom separated from the mug.”

Tests conducted on the objects found – a woman’s ring made of gold and a necklace wrapped in a piece of canvas – have concluded the pieces were made in Poland between 1921 and 1931.

The Auschwitz-Birkenau State Museum, which was founded by resolution of the Polish parliament in 1947, is devoted to the memory of the murders in both camps during World War II.

Between 1940 and 1945, about 1.1 million people, mainly Jews but also Poles, Roma and other nationals, were killed in gas chambers or died from forced labor, hunger and disease in the camp operated by Nazi Germans.