In Norse mythology, Jörmungandr, also known as the Midgard Serpent or World Serpent, is an unfathomably large sea serpent or worm who dwells in the world sea, encircling the Earth and biting his own tail, an example of an ouroboros. As a result of it surrounding Midgard it is referred to as the World Serpent.


I found this on Google. Is that what you had in mind when writing this story? Because if that's it, then the world is in trouble