The three witches were in the form of a swan with one eye and one tooth that they shared. Perseus stole the eye and the tooth and refused to restore them unless they told him where the Gorgons were to be found. When they told him, he threw the eye so they could not warn the Gorgons of his arrival. For this undertaking, Perseus got a magic shield from Athena as a gift, and the winged sandals and a sickle from Hermes; the Nymphs, instead, gave him an helmet that would have make him invisible and a sack in which he could put the head of Medusa.
