Paraguayan Lancer Helmet
This example is the same basic shape of the Paraguayan Cavalry helmets that were used from since the end of the 19th century. This is probably a post WWII example, but it is still a unique helmet.
Dress helmet of the 4th Cavalry Regiment of 'Acą-Carayą', which saw action in the War of Chaco (1932-35) against Bolivia. This example is from the post World War II era, but maintains the basic shape. The original helmets actually had monkey fur at hte top of this lancer helmet, but this was wisely replaced with something that just resembles it!