This content is exclusive to Pixel Gun World. It isn't in Pixel Gun 3D!
The Crown Of Discoverer's, also called the Discoverer's Crown, is a hat introduced at the start of the Open Beta Test of Pixel Gun World. It is one of the two rewards (the other being the Golden Friend) for all of the players who have participated in the Closed Beta Test of the game.
It seems to be a large crown, which contains rubies and emeralds. However, it looks pretty similar to the Destructor Crown.
It has a chance to ignore a headshot.
It increases the damage of all of the weapons.
It increases the mobility of all of the weapons.
Use this in order to reduce the amount of headshots.
It doesn't matter if you use average-damage/mobile weapons, because this crown will improve the damage and the mobility of any weapon.
Use area damage weapons in order to pick them off from a certain radius.
Taking them out with headshots will not give you the headshot achievement. It will only deal extra damage.
This is the first hat being exclusive to Pixel Gun World.
It looks pretty similar to the Destructor Crown.
This hat is obtained only to the players who have participated in the Closed Beta Test of Pixel Gun World.
Unfortunately, now that the CBT has ended a long time ago, it is impossible to get this item, effective December 8 2015. The same explanation for the Golden Friend.