This article provides initial results on the use of shellfish by the inhabitants of Clos des Châtaigniers, Normandy (France) during the Late Bronze Age. The settlement is located at Mathieu, 10km from the coast. The French National Institute of Preventive Archaeological Research (INRAP) conducted excavations on this site in 2010, under the direction of David Giazzon. A semi-circular domestic enclosure from the end of the Late Bronze Age was discovered. The diet of the inhabitants of Mathieu was partly based on mussels, which were found in large quantities. These shells were collected at low tide on a rocky to muddy/rocky shore. They were then transported inland to be eaten fresh or processed. Other marine invertebrates were also present on this site. Some of them were collected with the mussels. In fact, they were mixed with or fixed to this bivalve. Many other small fragments of shells are present on the site and could have come from the stomach contents of fish.