During Japan’s Warring States period, armorers developed a new, simpler helmet design, which had fewer (incidentally) ornamental features — ribs, ridges, rivets, etc. — and so they purposely developed the new streamlined helmet into the extremely ornate kawari kabuto, or strange helmet:
To offset the plain, utilitarian form of the new helmet, and to provide visibility and presence on the battlefield, armorers began to build fantastic shapes on top of the simple helmets in harikake (papier-mâché mixed with lacquer over a wooden armature), though some were constructed entirely of iron. These shapes mimicked forms from Japanese culture and mythology, including fish, cow horns, the head of the god of longevity, bolts of silk, head scarves, Ichi-no-Tani canyon, and axe heads, among many others. Some forms were realistically rendered, while others took on a very futuristic, modernist feel.
Some of these examples are amazing: