New Mob

It's a new mob called Phix, and they only appear at night time in the water in the swamp bio. They are not tamable but could offer you something at random, if you give an item (any item) they will give you something at the same value as the item you gave, or if you are lucky ( 0.15% ) they would give you something even more valuable ( oak wood = birch wood) ( lucky: oak wood = wooden pickaxe ). Its features could be a limestone color or grey coat and the hair could be cave vines or moss and it will be like just half a head ( from the top of the head to the eyes ) poking out of the water and just swimming around. To get their attention, pull out a mushroom and give it to them( they will stay still for a good 2-3 mins ). You can trade only 4 times before the mob swims away and doesnt return until the next night