International audience The picture of the Alexandria’s lighthouse equiped with four tritons at the corners of its first floor is quite characteristic of the representations figured from the Ist century p. C. These tritons accompanied by their conch are an Alexandrian specificity, since they are not found on any other lighthouse of the Antiquity. This work brings together a rich textual, iconographic and conchyliological documentation of the Triton(s). The conch, a marine sonorous instrument, becomes the main attribute of this divinity in connection with navigation. It’s in a prolific context that the Alexandrian engineers choose to automate these divinities benefactors of the maritime world to create a real harbour signal.