Anonymous donor of NMI artefacts & #treasure sought to help determine where these were found. #InformFutureResearch https://t.co/LEgo3mjos3 — Archaeology @ITSligo (@ITS_Archaeology) December 28, 2016

Recently, the main Dublin branch of the National Museum of Ireland, which focuses on archaeology, received a series of mysterious envelopes addressed to “The History Museum, Kildare St., Dublin.”

The envelopes were brown and had no return address or postmark. Inside, museum staff found four fascinating objects dating back thousands of years into Ireland’s past.

Two of the items were axes from the Bronze Age, one about 3,300 years old and the other more than 4,200. The other items were more recent—rare Viking jewelry that might have come to Ireland from Norway.

The museum believes the items may have been excavated using a metal detector, without the necessary license. In Ireland, it’s illegal to use a metal detector to search for archaeological objects, and without a “Detection Consent” permit, finding an archaeological object using a metal detector is subject to a hefty fine and possible prison time. (If a person finds an archaeological object accidentally, while they’re, say, digging in a garden, that’s okay.)

Despite the illegality involved, the staff is hoping the finder will come forward so that they can learn more about the context in which these objects were discovered.