The GillyGaloo Bird - [Fearsome Critter]
• About this Critter: A small, mythical bird that lays perfectly cubed eggs (complete with divots) so that they wouldnt roll down the high-slopes of where they nested. Lumberjacks would hard boil them and use 'em for dice n' gambling.
• History: The 'GillyGaloo' was first named as a 'fearsome critter' in Paul Bunyans natural history  (Though records show that the name was being used and in the public consciousness as early as 1899.) - The description included in Paul Bunyans natural history goes as follows:
GILLYGALOO. - "This hillside plover nested on the slopes of Bunyan's famous Pyramid Forty. Living in such a locality it laid square eggs so that they could not roll down the steep incline. The lumberjacks hard boiled these eggs and used them as dice."
Pauls famous "Pyramid forty" is of course a recurring location in most of the early 'Paul bunyan canon', most famously it refers to a huge, pyramid shaped mountain with trees that where so vertical & thick that even Paul couldn't get over it! so he had his trusty seven axemen do the work for him. –
[Snippit from Paul bunyan tales 1922, technically the first mention of the birds.]
• Variants: Occasionally the Gillygaloo is instead imagined alternatively as a sort of flightless Penguin (Whos square eggs hatch only when left in the coldest snow.) - in such cases it is more properly referred to as the "Deep-Winter-Flying-Midget." [Rockwell, J. E. 'Some Lumberjack Myths', The Outer's Book, February 1910.)] - there are of course, numerous other birds by many other names that lay 'square eggs' across folklore & pop culture as well, but because I am short on time, I wont list them all here today. [note to self: come back and edit this part with more later]
In my youth, I occasionally met people who would use "You Gillygaloo Bird!!" as a sort of derogatory slang to refer to 'a woman who is a jerk' it was used like how 'bird' is sometimes used derogatorily [oddly 'bird' as an insult it seems to be a a British thing?] - for some reason, I always pictured the Gillygaloo as a square bodied old timely, card dealing bird.