The Galea is the headwear used by the Centurion Zombie that appears in Penny's Pursuit in Plants vs. Zombies 2. It works similarly to the knight helms that Knight Zombies use, but it absorbs way more damage than it. A Magnet-shroom can render it useless since the galea is a metallic object.
The galea abosrbs 1950 damage per shot and degrades at 650 and 1300 damage per shot.
See Centurion Zombie.