The trochilus or trochilos (Greek: τροχίλος, trokhílos = "runner"), sometimes called the crocodile bird, is a legendary bird, first described by Herodotus (c. 440 BC), and later by Aristotle, Pliny, and Aelian, which was supposed to have enjoyed a symbiotic relationship with the Nile crocodile: it was said to pick leeches from the crocodile's throat by Herodotus, and to pick the crocodile's teeth by Aristotle. The trochilus has subsequently been spuriously identified with several bird species endemic to the Nile valley.