bimaman said: It's interesting o see that someone remembered that the original Alien head was semitransparent and had a deformed human skull inside.
I think that was Carlo Rambaldi's contribution to the original design... He designed the first costume and to make it functional and realistic he used a human skull to make the face and part of the head. Hans Ruedi Giger did the original design of the xenomorph and supervised Rambaldi's work...