It's a machine. Look at, look at the bottom where the damage is. Also, the fallen call it the great machine. Who built it? No one knows. But it has sentience so it is aware, like exos or ghosts are. Read grimoire for ghosts. I believe that is a card discussing the creation of the traveler by the "powers that be". I believe the traveler to be the referenced "topologically creative enclosure". It also implies that the inside of the traveler is sealed away from space and time, and that someone/something is inside but can't see out. Of course, this assumes that card is about the traveler, but I believe it is.