The Remnent appears to be some sort of switchable panegate or twistpoint, but rather than having a lock it accepts voice commands and will answer requests for information. It exists amongst the subshafts, and thus far has only been seen to connect to other areas of the subshafts. Cully and Tuttle pass through it to get the HJ42. It is "almost certainly" the last surviving fragment of what the subshafts originally were, according to Tuttle.