Different authors give different etymologies of this word. Some derive it from the Greek άγκύλοσ, "crooked". Varro derives it ab Ancisu, as being cut or arched on the two sides, like the bucklers of the Thracians, called peltæ. Plutarch thinks the word may be derived from the Greek άγκών, "elbow", this weapon being worn on the elbow. The opinion of Varro, however, is more probable.
Though there was but one Ancile that fell from heaven, there were twelve preserved, called the Ancilia; Numa, by the advice, as it is said, of the nymph Egeria, ordered eleven others, perfectly like the first, to be made. This was so that if anyone should attempt to steal it, as Ulysses did the Palladium, they might not be able to distinguish the true Ancile from the false ones.
These Ancilia were preserved in the temple of Mars, and were committed to the care of twelve priests of Salii, instituted for that purpose. They were carried every year, in the month of March, in procession around Rome, and on the 30th day of that month, were again deposited in their place.