Are the Kyuss Worms undead?

[Paul Murray]

Are the Kyuss worms undead? Can they be detected with a detect undead? Will Hide From Undead work against them? Can they be turned or destroyed? What's their HD for purposes of determining if a cleric can turn them? If there's a writhing mass of them, how many HD per 5' square are there for purposes of determining how much a cleric turns?

[Mothman]

Argh, website ate my post. I’ll try again.

According to the Ecology of the Spawn of Kyuss article in a back issue of Dragon, and various discussions on these boards,

Spoiler:

Kyuss worms are vermin, not undead, and therefore cannot be turned etc.

[Paul Murray]

Hmm. Perhaps I might at least make 'em magical creatures that radiate an aura of necromancy (for the arcane casters) and evil (for the divine casters).

[Eltanin]

Why worry about the aura of necromancy etc.? Most of the time, the Kyuss worms are inside another creature which is an undead creature. There are only a couple of cases where you might encounter them outside something undead, and the literature (online and published) is pretty clear that they're vermin. That's why the spell Repel Vermin works on them.

I'd say don't mess with it. Your players won't need any more information about them.