Suetonius Caligula 46

At last, as if resolved to make war in earnest, he drew up his army on the shore of the ocean, with his balistk and other engines of war, and while no one could imagine what he intended to do, on a sudden commanded them to gather up the sea shells, and fill their helmets and the folds of their dress with them, calling them " the spoils of the ocean due to the Capitol and the Palatium." As a monument of his success, he raised a lofty tower, upon which, as at Pharos, ¹ he ordered lights to be burned in the night-time for the direction of ships at sea; and then promising the soldiers a donative of a hundred denarii ² a man, as if he had surpassed the most eminent examples of generosity, "Go your ways," said he, "and be merry; go, ye are rich."