A Pileus originated in Greece but was introduced and adopted in Rome even before the 5th century BC. It is a conical, brimless hat that was worn to cover some portion of the forehead, if not all. Pileus was originally made from felt and was therefore soft and comfortable.
Later on, the design was also adopted for infantry helmets and thus was made using metallic materials such as bronze. Further, it also had a horsehair crest on it.
A pileus also symbolizes freedom as it was used in the liberating ceremonies of prisoners in ancient Rome.