In 1999, underwater excavation by the European Institute of Underwater Archæology (IEASM), in the Bay of Abukir, brought to light new fragments of a naos known since the early 19th century as The Louvre Calendar. It was later called The Naos of the Decades because of the very particular decoration of its outside surfaces which were separated into frames, one for each group of ten days of the ancient Egyp­tian year. This new discovery was the third one in the series of archæological episodes which allowed in the course of over two centuries to nearly complete the reconstitution of the monument: the roof of this naos was found in 1777 on land and belongs to the Louvre Museum; the base and the rear wall were found in 1940 under water in the Bay of Abukir, and our newly found items complete the major part of the lateral surfaces. Despite their stay of over one thousand years in salty water, the inscriptions preserved fairly well on the new items contradict the previously assumed distribution of the decades on the walls, and above all, shed an entirely new light on the interpretation of this important monument.