Horsehair "plume"

[Magnus]

Depends on what legion you're doing and where they were stationed in the 2nd century. Chances are crests didn't just abruptly die out in the 2nd century, only to reapear in the 3rd. But considerations should be taken on whether or not your legion was involved in the dacian campaigns. If so, then there's a good chance that the crest mount would have been adapted to fit over rudimentary crossbracing on the helms being used. I don't think crossbracing on helms have been found in say...britain or the gallic provinces.