Black Thread

Black thread is a special material crafted by magically inclined priests and priestesses of the Spider Cult. It is primarily used in reanimation. A thick, potent threading that can sew bodies together more seamlessly and are resistant to degradation, preventing the newly created corpse-construct from falling a part as it would if it were using normal threading.
The material is made from spider silk primarily. Silk that is produced by spiders who have been magically altered to generate larger quantities of silk than normal spiders. Every temple to the Spider Goddess has a spider garden in the temple courtyard where these spiders are born and cultivated so that their silk can be harvested by the lower level priests. The spiders themselves are non-venomous, though their bite still itches terribly for days after the bite.
After this the silk is soaked in black blood, giving it the iconic black coloration for which the silk is known. Then is is empowered by prayers to the Fateweaver herself who endows the thread with some of her godly strength, making it incredibly resilient and unable to degrade from weather or natural born bacteria. The thread cannot be cut without the use of magic which allows it to permanently bind flesh together when used in stitching. Unfortunately it is also slightly toxic to living people and as such cannot be used medically. Only the undead can use the stitching without growing sick.
Large amounts of the black thread is produced every day all across the world and sent to hospitals to be used by reanimators in curing the condition of death. Even those who do not ascribe to the Cult of the Spider’s faith can be gifted it through reanimation as all undead are viewed as children of the Spider Goddess regardless of who they were or are before or after death.