Keshog

Keshogs are omnivorous, worm-like creatures that reside in the outer wilds of Tellus. Keshogs are rarely seen, as they live underground away from danger, they only surface to eat plants or snag creatures, where they will try and pull them down underground.
  Most commonly, keshogs will not grow overly large, averaging about 3ft in length; however, in rare circumstances where a keshog finds sufficiently large feeding grounds for long enough, they can grow up to 22ft long, and large enough to consume a person whole, where they will then be able to eat more and more as they grow to greater lengths.
This has led to a few occasions in history where what are named "Death Worms" will grow to legendary sizes, apparently able to grab entire Luxon and drag them down into their domain. If this were to happen, wealthy traders would likely put out great bounties for people to slay the Death Worm, as they greatly disrupt caravans and trade routes that they make their money from.
  The name 'Keshog' is the Urkali name for the creatures, adopted by many as the standard term, however, they are also commonly referred to simply as 'Fog Worms'.