Bone spiders were sentient arachnids.
Bone spiders were huge white spider-like creatures of bleached bone. They had eight legs, eight white eyes and distended abdomen. Unlike Earth spiders, their eyes had eyelids that closed with a bone tick resembling a camera shutter. Bone spiders possessed scary fangs.
Bone spiders could make dreams, memories and fears tangible, down to the smells. They could not distinguish between good dreams and nightmares. A touch of a person the nightmare originated from turned it into dust.
The spiders could not talk but could communicate by dreamweaving images and scenes.
Bone spiders could also create a thin layer of web around a person that would make them invisible and inaudible to others. Two individuals both rendered invisible, however, could communicate to each other and see and hear the rest of the world without difficulty. Even so, the spiders could conceal themselves also from people rendered invisible. The visibility could be restored by cleaning the spiderwebs away, but it took a lot of time.
Their spiderwebs of bone spiders could also be visible and as thick as football socks. They could be spun very quickly and prevent doors and windows from opening. They were also used to quickly cocoon a person completely immobilising them.