In Sandworms of Dune , Brian Herbert and Anderson's 2007 conclusion to the original series, the Spacing Guild is manipulated into replacing its Navigators with Ixian navigation devices and cutting off the Navigators' supply of melange. Sure to die should they be without the spice, a group of Navigators commissions Waff , an imperfectly awakened Tleilaxu ghola , to create "advanced" sandworms able to produce the melange they so desperately require. He accomplishes this by altering the DNA of the sandtrout stage and creating an aquatic form of the worms, which are then released into the oceans of Buzzell . Adapting to their new environment, these seaworms quickly flourish, eventually producing a highly concentrated form of spice, dubbed " ultraspice ". Meanwhile, sandworms are revealed to have survived the devastation of Rakis after all, by burrowing deep under the surface.