Shapeships were spherical Void Ships originally developed by the Space Lords of Fractallax.
Near the start of the Cosmic War, the Space Lords "liquidated" a fleet of Shapeships, which ended up being bought wholesale by the posthuman Plume Coteries to replace their Birdhemoths, who were losing the ability to fly reliably due to having spent too long cooped up inside the Library. (PROSE: The Cactus and the Corpse [+]Loading...["The Cactus and the Corpse (short story)"]) Such a "boring metal sphere" was indeed used as a Plume Coteries diplomatic craft by at least one Bookkeeper during the War in Heaven. (PROSE: A Farewell to R.M.S. [+]Loading...["A Farewell to R.M.S. (short story)"])
Behind the scenes
Though the name debuted in The Cactus and the Corpse [+]Loading...["The Cactus and the Corpse (short story)"], a story by Aristide Twain, the copyright blurb of Horrors of Arcbeatle credited Shapeships to Nate Bumber.