Paleotechs
In an interstellar gulf, a ship dropping out of hyperspace to make an essential repair discovered a (presumed) dead Paleotech. The apparently lifeless hulk took the form of a thin-walled tube half a million miles long.
Kin Arad, in her filmy Continuous Creation, has, however, pointed out that paleotechs are on a different scale to humans in terms of time as well as size. This Paleotech may well be atill alive, on a cosmic scale, if considered by the standards of slow metagalactic Time. Like an old troll on the other Discworld, it might well be having a good long philosophical ponder on the meaning of existence...