Mark 9:47-49 (YLT):
47 And if thine eye may cause thee to stumble, cast it out; it is better for thee one-eyed to enter into the reign of God, than having two eyes, to be cast to the gehenna of the fire -- 48 where their worm is not dying, and the fire is not being quenched; 49 for every one with fire shall be salted, and every sacrifice with salt shall be salted.
This is widely understood as Jesus quoting Isaiah 66:24 (YLT):
24 And they have gone forth, And looked on the carcases of the men Who are transgressing against me, For their worm dieth not, And their fire is not quenched, And they have been an abhorrence to all flesh!
However, worms are mentioned in Isaiah 14:9-11 (YLT) too:
9 Sheol beneath hath been troubled at thee, To meet thy coming in, It is waking up for thee Rephaim, All chiefs ones of earth, It hath raised up from their thrones All kings of nations. 10 All of them answer and say unto thee, Even thou hast become weak like us! Unto us thou hast become like! 11 Brought down to Sheol hath been thine excellency, The noise of thy psaltery, Under thee spread out hath been the worm, Yea, covering thee is the worm.
Are all these worms related? Do they all belong to the same kind of worms? Are the contexts of Isaiah 14:9-11, Isaiah 66:24 & Mark 9:47-49 the same or at least related in some manner? Are these worms literal or allegorical?