The ruins of Porphyreon should be found near Belus, the Nahr Namein, in the sands of which may still be seen the murex brandaris and the murex trunculus (thorny shell fish), from which is extracted the famous purple dye of Tyre, and which gave its name to Porphyreon.
What Theodotus accomplished at this time we know not, but the next year (219 BC) we find him serving under the immediate command of Antiochus himself, and bearing an important share in the action against Nicolaus the general of Ptolemy IV Philopator (221–204 BC), near Porphyreon, as well as shortly after at the siege of Rabbatamana.