I heard they were going to make a prequel to "Alien" that explains the race of people that first invented the Alien creatures. Can't recall if it's extended footage or in the original film since it's been a long time but there is an image a giant space creature / pilot (not the Alien) sitting in a big funky chair of the crashed ship where the Alien eggs were first found. That pilot had an exploded chest, indicating an Alien had come out his chest, just like they do for the humans later.
I also think there is something about the Alien creature was manufactured but got out of hand and turned on it's creators.
It's been a while so I might be fuzzy on the details.