a waxy substance found floating in or on the shores of tropical waters, believed to originate in the intestines of the sperm whale, and used in perfumery as a fixative
The definition of this word alone isn’t really enough to understand why it’s on the list. The Wikipedia page helped a bit, though. Whalers, and alchemists would be interested in it for trade, and it could also be a rather disgusting place to hide loot. Fantasy settings can have creatures other than sperm whales that generate a similar material as well. The most likely settings to use it are sea settings. Games and stories about pirates come to mind.