The worm is a parasitic organism (although it can be argued that it is symbiotic, considering that its use by the Sykaran resistance has beneficial side effects for the host) that is used by the Sykaran resistance to render themselves immune to the mind-altering effects of Tannot Root. The worm is inserted into the body through the navel; there it attaches itself to the host's digestive system, where it filters the mind-affecting elements of the Tannot root out of the host's system before it can be metabolized, thereby rendering the host unaffected and able to think freely. It is therefore used by the Sykaran resistance as an immunization agent against the mind-altering effects of Tannot root. After the worm has infested a host, it will bring pain to the host unless they eat. The worm is very rare.
Immunity to the Tannot root's mind-altering toxin, either naturally or through the hosting of a worm, is illegal on Sykar, and is a capital offence. It is therefore vital that anyone hosting a worm does not reveal that they are infested, and must always attempt to display the symptoms of a being under the influence of Tannot root poisoning, or risk being discovered.
The worm can be removed fairly easily, although it is apparently rather painful. ("Thank God It's Friday... Again")