<Li> Imperial Italic helmet (late 1st BC - early 3rd century AD) </Li> <Li> Ridge helmet, first depicted on coins of 4th - century AD emperor Constantine I . </Li> <P> Some of the helmets used by legionaries had a crest holder . The crests were usually made of plumes or horse hair . While they are usually shown in red they probably occurred in other colors, like yellow, purple and black, and possibly in combinations of these colors such as alternating yellow and black . </P> <P> There is some evidence (Vegetius writings and some sculptures) that legionaries had their crests mounted longitudinally and centurions had them mounted transversely . Crests may have been worn at all times by centurions in the early Empire, including during battle, but legionaries, and centurions during other periods, probably wore crests only occasionally . </P>

What is the hair on top of a helmet called