Silver cord

Many dreamers, soul flyers, and astral travelers report that when their spirits are separated from their physical bodies, the former remains tethered to the latter by means of a silver cord: a silver-colored ethereal thread that is (seemingly) infinitely stretchable and connects the person's spirit-body to their comatose physical body.

Silver cords are believed to be indestructible—with a few exceptions. For example, it is believed they can be severed by the silver swords of the githyanki.