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@S.M

That's true! The Space Jockey was actually omitted from the ALIEN novelization!

As far as the Alien 3 Face Huger and Blood, i think we cant rule out that the Organism can produce this Acid for other reasons.

Like Kanes Mask, the Face Huger had to produce Acid to be able to burn a hole into his visor so that the Organism could get to Kanes Face...

So its possible the Face Huger and secrete Acid to allow it to get to a Host.

True it definitely seemed to burn through Kane's helmet, and we can imagine the same happened here, even though the pod cracks and later looks broken, not burned. Plus a lot of acid seems to spill, but none is visible in the tube and Ripley is unharmed, but then again the same was also true of Kane. That's why I said it was the less obvious inconsistency. The point is: I maintain that whether or not it works, it's a plot element, and initiates the story.

Yeah thats true..

The crack could have happened as a result of the crash into the Sea?

The hugger got cut by the cracked tube glass, and the acid started the fire.

"Anyway, this is confusing the only point I was really trying to make, that I highly doubt there is a franchise-wide secret sub plot tying all this together."

Quite.