The Coggalbeg treasure is an early Bronze Age treasure from Goldwork Jewellery dating from 2300-2000 B.C. It was found in a swamp at Coggalbeg in the Irish county of Roscommon in 1945, and consists of a gold moon ("little moon" shaped like a half moon) and two small gold discs known from other countries. Patterns decorated with a cross inside the two circles. The pieces are flat and thin, and the total weight is less than 78 grams (2.8 oz.), indicating that they were probably intended as part of a necklace.
The treasure was discovered in 1945 by Hubert Lannon while he was cutting sod on his swamp at Roscommon. From 1947 it was kept in a safe at Sheehan's Chemists in Strokestown, during which time only members of the Sheehan family saw it. After a break-in at the pharmacy where the safe was stolen, Garda Siochana (Irish police) found the paper-wrapped items in a trash container in April 2009. It is believed that the thieves were primarily interested in cash and were unaware of the items in the discarded loot.
Today it is in the National Museum of Ireland, where it is on permanent display. According to Mary Cahill of the museum, these objects are significant as the only surviving "association between discs and lunula, because discs would be considered some of the earliest gold jewelry, and lunula would come a little later." Of the approximately 100 European lunula known in Western Europe, about 80 come from Ireland. In 2017, these three objects were featured on an Irish postage stamp, one of a series showing the history of Ireland in 100 objects.