Bronze copy of the Delphic E, an ancient Greek symbol (key) that was related to the initiation of man into the light (For this reason it was in the Temple of Apollo in Delphi, where the worship of the Sun was held (Apollo was the god of the Sun)) and symbolized a shape : union and trinity (three parallel lines united).
as a number: the 5 cosmogenic elements Earth, Air, Water, Fire and Ether (quintessence)