Bromine Lake is a lake that is almost a very small inland sea. It is also special for other reasons. It always has the warmth of a living Human, no matter what the season. It is not a hot spring with its sulfuric chemicals. There are hundreds of theories, but no answers.
Even if they did, they would never believe it, as it has ties to the time of legends, to the time of Corvus.
Arakis's zombie problem went largely ignored, because it was believed that the Shai-Hulud (sand worms) would effectively dispose of the undead walkers. Unfortunately the problem grew until the roving herds of sunburnt ghouls threatened the flow of spice. While observing one of the great reanimated masses over take a Harvester from the safety of an ornithopter, an Imperial Zoologists noted that the sand caked flesh eating revenants walked entirely without rhythm.
Shortly after receiving this report the Bene Gesserits claimed to have a solution to Arakis's hellish resurrections. They asserted to the agents of the great houses that the worms could be drawn to the walkers using an ancient sonic weapon. According to the sisters, exposing the zombies to an antediluvian ballad composed by the great master M. Jackson would force them to step in time.