Norse Myth of a guardian worm I remember reading a picture story centered around Norse mythology when I was a child. A Princess or noble women get possession of a Worm that quickly grows so large and powerful it traps the Princess in her tower. The King promises half his kingdom to whoever can slay the Worm, however, the Worm's blood is hell-a toxic and kills the Knights that manage to cut it.
The worm is only defeated when a lad undoes the head from his spear to act as a plug after landing, protecting him from the pour.
The origin's been bugging me forever. I don't even know if it's real myth or some story.