A genetic variation of the Sandworm which was originally found on Rakis, created by the Tleilaxu Master Waff, in an ultra secret Guild laboratory.
The ghola of the Tleilaxu Master, Tylwyth Waff, was imperfectly awakened by the Honored Matres leader Hellica, in the Tleilaxu city of Bandalong. After the attack of the New Sisterhood on the ghola complex, Waff escaped with the help of the Guild Navigator Edrik, with Waff's promise to create a genetically altered sandworm for the Guild to use.
Waff was successful in altering the DNA of the sandworms, so that they did not become averse to water as they matured out of the sandtrout phase. The Guild commissioned Waff to release some immature "seaworms" into the ocean world of Buzzell, where they quickly flourished. They grew large and strong, and took over the planet's eco-system, killing many of the native cholisters and Phibians, who were more native to the water world.
Later, Waff and his Guild assistants returned to Buzzell, and captured and harvested one of the giant seaworms. As Waff gutted the seaworm on the beach of an island of the planet, he found in a liver-like organ of the worm, an organ-cache of Ultraspice, a concentrated version of normal melange. The seaworms continued their over-taking of the eco-system of Buzzell, and eventually came to dominate it.
The ultraspice was initially given to the Guild, stolen by Khrone and the Enhanced Face Dancers, and turned over to Omnius and Erasmus.