Original: The name "Nautilus" originally referred to the Argonauta, otherwise known as paper nautiluses, because the ancients believed these animals used their two expanded arms as sails (cf. Aristotle Historia Animalium 622b).
Simplified: The name "Nautilus" originally referred to the Argonauta, otherwise known as paper nautiluses, because they allegedly use their two expanded arms as sails (cf. Aristotle Historia Animalium 622b).