the “Coolus” variety, which covered the period 3rd century BC to at least 79AD. These were based on a Gallic form of helmet made in the Coolus district of Marne. In form they were a simple hemispherical bowl made out of bronze with a reinforcing peak running horizontally across the brow and with a larger extension at the back as a neck guard. Most have a simple spike as a plug-in plume or crest holder.