Teutonic Knights you say? Well yes, the crazy crested helms existed. I sport one myself. You see, while crests do make wonderful levers in the heat of battle, many were mounted to easily come off without any serious harm to the wearer. They serve a very practical purpose of identifying leaders in battle, where a surcoat might be obscured by bodies in the fray, a crest would rise above the line of heads, so that the soldiers would know their leader lived.
Among the Teutonic Knights, only leaders would be granted permission to wear one (I myself portray the Grosskomptur, the 2nd highest office within the Order in the Beauseant Brotherhood, and for Living History, I portray a Komptur, a district leader) and since they sacrificed personal heraldry to enter the Order, often the crest would take a strange shape, like wings, a fist, a wolf's head, horns, ect.
Hope that helps.