While this may not be useful for direct encounters, I think the presence of these critters would provide excellent flavor for a region in some campaign world.
Of course, it could be that they provide necessary ingredients for some alchemical concoction that the PCs desperately need, or that one has swallowed an important item (possibly while ridding itself of an annoying scholar) which must be retrieved.
<i>The Wax Candle Caverns
To sail through the remains of Rivallo the Scribe is a most unusual experience. The unlikely cave system is often attributed to Rivallo's habit of studying late into the night with only a candle for company. A beautiful but flickering system of caverns carved from wax by man-sized wicks, whose silent flames lick the high-arched roofs, is all that is left of Rivallo's fertile imagination. Boats proceed slowly through the hot, thick wax, which drips in a slowly descending series of rivulets down the intricate labyrinth</i>