For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Kenneth Heck
Here is my belief, unsupported by much scripture. This scripture tells us of the condition of those have transgressed against the LORD at some time in the future. The "worm" here is the part of the soul able to feel pain. Even a worm will have a spirit of sorts which gives it life and a nervous system able to feel pain, but nothing emotionally or mentally. This part of the soul (or spirit) after death can be lost because "the wages of sin is death" (Rom 6:23) for both body and soul. The second death is the death of the soul, either partially or completely (Rev. 2:11). So the transgressors will be in severe pain eternally because the fire causing pain is never quenched and the worm aspect of their soul doesn't die normally, perhaps because the Beast or False Prophet gave them a spiritual gift and false hope for resisting the fire after their bodily death.
cheryl richardson
Mark 9:48 where the worm never dies.
With these strange words, Jesus pictured the serious and eternal consequences of sin. To the Jews, the worms and fire represented both internal and external pain.