Unfortunatly its the closest we'll ever get to an answer.
Also would explain the angle and strange look of the egg. And we don't see all of the subflooring in the whole bay, there could be an area under that floor where this egg is.
And if you think this is crazy, read Gibsons Alien 3 drafts. The egg literally grows out of bishops abdomen because the queens tail left the micro egg goo behind.