The heroes find the crumbling, overgrown ruins of what appears to be some sort of grand dining hall in the forest. Deciding that it is a good place to camp, the set up a fire in the center. However, they are woken in the night to see skeletons waltzing in the moonlight to organ music that emanates from the open air. The skeletons touch nobody, dancing around them all night.
These rare, fist-sized spiders do not make webs, but rather excrete secretions which harden upon contact with air. These "droppings" resemble barley-sized spider eggs, or even lustrous pearls, once the slime coating them, dries up. In fact, dried Pearl Spider "drops" are indistinguishable from the marine varieties produced by mollusks, and hence of identical value on the open market!
Several centuries ago, they were studied by naturalists, and several observations were made. Firstly, was that these spiders "lay" these pearls for no apparent or discernible "natural" reason, and secondly, the naturalists had discovered that the more these spiders ate or were fed--and they were true omnivores--the larger the spider pearls came out.
A cottage industry began. Enterprising merchants hunted and collected these creatures across the lands, erecting spider-farms for the manufacture of Spider Pearls. It wasn't long before someone got the idea to force-feed the spiders, ala foie gras geese, and soon, the fattened spiders began pooping out pearls of great size! (relatively speaking). The regular pearl market came to disarray, and prices and value fluctuated wildly.
[b]Plothook[/b] The Mermen Mercantile Alliance hires the party to eradicate all terrestrial Pearl Spider Farms!