Skyslugs were filthy vermin that roamed Open Sky. Skyslug was also a common swear word in the Second Age of Flight: Deadbolt Vulpoon called Vox Verlix a 'slimy skyslug' for swindling him out of a consignement of bloodoak in Freeglader while in Vox, Xanth accused Mollus Leddix of being an 'evil skyslug' for sacrificing Librarian Knights he'd intended to free for one of High Master Orbix Xaxis' rituals.