Peter Jackson has gone on record regarding his arachnophobia, and no one who saw Shelob in Return of the King (the movie, she showed up in the pages of The Two Towers it's complicated) will doubt this. And while the spiders that spin their webs under the eaves of Mirkwood are described as Shelob's lesser brood, there are a lot of them. And if there's one thing creepier than a giant spider that wants to paralyze you and eat you alive, it's HUNDREDS of giant spiders that want to paralyze you and eat you alive. But more than a fascination with monsters, these creatures represent a major turning point in Bilbo as a character and his place in Thorin's company. It is during the encounter with the giant spiders that Bilbo will name his sword and earn his place among these dangerous warriors he's been traveling with.