What spice is the most essential and valuable commodity in the "Dune" universe?

More Questions:

In the North American market, what is the difference between hard and sweet cider?

From what country did the US buy the Virgin Islands?

What Parisian hill is home to the Moulin Rouge and the Sacré-Cœur Basilica?

When standing in sunlight, what vitamin does your body synthesize?

Which British designer invented the Dual Cyclone bagless vacuum cleaner?

What large reptile was popularized by Steve Irwin and Paul Hogan?

On what TV show did the characters often hang out at the Warsaw Tavern?

What genre is Neil Young considered to be the grandfather of?

Which staircase in the Leaning Tower of Pisa has fewer steps?

Who conquered the Matterhorn in 1865?

What year was Albert Einstein born in?

When was Cable News Network, or CNN, launched?

Which islands were the subject of a war between Argentina and United Kingdom in the 1980s?

What is agrostology the study of?

Which band released the song "Proud Mary" in 1969?