Were the Hobbit-Five armies rock-eating-worms a Jackson invention or do they have a precedent in middle earth Lore?

Question

In the Jackson movie "Hobbit - The Five Armies" there appears to be a race of rock-eating worms (similar to Tremors) that assist the Orc army.

Now I'm aware Jackson is contractually barred from using Silmarillion material.

I'm also aware that throughout the books, the dragons are referred to as 'worms' - and that in the 'hierarchy' of Middle Earth - Balrogs are similar to an Istari ('lower angel') similar to Saruman, and Dragons are on the same level as Orcs (not an Istari).

We also know that the Orcs, Trolls and Goblins were the constructs of Morgoth/Melkor, which he had made by corrupting and breeding humans, Elves and other creatures.

My question is: Were the Hobbit-Five armies rock-eating-worms a Jackson invention or do they have a precedent in middle earth Lore?

Answer 1

These appear to have been an amalgam of two concepts from the books.

First of all, the Were-worms themselves are mentioned in The Hobbit (and it's notable that Gandalf calls them "Were-worms" in the movie too):

Tell me what you want done, and I will try it, if I have to walk from here to the East of East and fight the wild Were-worms in the Last Desert.

Secondly, in Gandalf's description of his fight with the Balrog in The Two Towers:

We fought far under the living earth, where time is not counted. Ever he clutched me, and ever I hewed him, till at last he fled into dark tunnels. They were not made by Durin's folk, Gimli son of Gloin. Far, far below the deepest delving of the Dwarves, the world is gnawed by nameless things.

So yes, rock-eating things do have precedent in Tolkien's writings, but making them be the Were-worms of The Hobbit is a Jackson invention.

Answer 2

In Middle Earth lore, we know Tolkien's dragons didn't have to have wings necessarily to be considered dragons. While Jackson may not be allowed to use material from the Silmarillion, Glaurung was the precursor to the 'Modern' dragons with wings. (http://lotr.wikia.com/wiki/Glaurung)

In the Appendix A-II of the Lord of the Rings, a dragon named Scatha is described as a long worm, who was killed by Fram, an early chieftain of the Rohirrim ancestors. The passage goes on to say the land was then free from long worms afterwards. This may or may not mean that Scatha belonged to a sub species of dragons without wings, since Tolkien said there was peace from 'long worms' specifically and not dragons. The problem is that Scatha was found on Ered Mithrin, and so it was mountain terrain and not really the kind of flat topography we'd expect the burrowing worms the movie depicted to prefer. (http://lotr.wikia.com/wiki/Long-worms) (http://tolkiengateway.net/wiki/Scatha)

However, in the Hobbit itself, Bilbo does makes a reference to a creature called a were worm, which supposedly lives in a desert in the east. So that would probably be closer to the version in the movie, and most likely where the earth-eaters as I think they were called originated from. The ability to chew through rock and compacted earth however, is not at all specifically mentioned within either LotR or The Hobbit to my knowledge.(http://lotr.wikia.com/wiki/Were-worms)

This ability to carve passageways underground could be more inspired from the 2003 video game based on and named The Hobbit, where were-worms are depicted as blind, subterranean dwelling caterpillar like critters. Who knows. Either way, wingless worms are mentioned in the books, not so much earth eating ones.(http://lotr.wikia.com/wiki/The_Hobbit_(2003_video_game))