what i meant was, if a facehugger infects 20 humans all of which are different race, age, sex, height etc the alien's would look 95% the same, but if the host happen 2 be a dog or whatever then the alien would differ like the dog-alien (runner) as seen in alien 3. As far as the tubes on the back, giger design it, it may have no meaning other than it look good! we as geeks look 2 much into things lol