Board Thread:Warhammer 40k General Discussion/@comment-6078851-20140531013206/@comment-69.35.168.121-20140603054353

I don't remember exactly when their powers of expectations came about, but it may have been a group mind vestigial organ scenario. If some of the orks were created before the real origin were, well, killed or whatever actually happened, then they would see other belly buttons. All it would take was someone telling an Ork that everyone used to have them, him thinking "I haz em" and sharing that idea, then suddenly everyone has one!

A much better theory, however, is that the pouches the Orks are born in are engineered to be a replica of a real organic one. Thus the umbilical cord would be needed in order to transfer those liquids into and out of the baby Ork. I mean, what do you expect, that they just absorb it from the casing through diffusion? Humans don't, despite presumably close embryo development when analyzing the late development.

To be short: the bellybutton would probably exist anyway because an umbilical cord is necessary to transfer liquids into and out of the developing fetus Ork.