The spoon bits are Weirder even than that...They're not led away by grain direction,somehow...
(i've forged them before,or tried to,with varying success...).
They're often used in odd applications like mortising for chair spindles and legs,where everything goes in at some strange angle...
I never understood how or why they'd differ from a twist-bit,or a barefoot screw-auger...but they sure Do.