Over a thousand years ago (eighth century A.D.), in the first epic poem ever written in English, "Beowulf", a monster with acid-blood was first depicted. In the story, the hero Beowulf cuts a she-monster, called the Seahag, in half. The Seahag's blood is so acidic that it completely melts the blade Beowulf's sword and eats a large hole in the cave floor. The concept was rather unique for its time, don't you think? I think that the acid-blood in "Alien" owns its origins from the epic "Beowulf". What do you think?