You might wanna think about adding some sounds to emphasise the danger element of the worm. Worms don't generally produce a sense of fear when confronted with them (although I'm sure a giant monster one might!), but something like a snake which is kind of similar in shape has a definite fear factor associated!
Maybe trying something like a hiss or rattle type sound could help with that. I remember in the new War of The Worlds film those tentacle/probe things had a sound like a rattle snake which helped add the sense of danger about them.
Perhaps layering in those types of sounds with some heavy whoosh sounds could be useful for the attacking element. Not sure how your worm in question moves about but something like a punch bag being dragged along a rubble/gravel type surface and pitched down might help add some more body and menace to it.
Hope that helps!