User blog comment:Darkcloud1111/Son of Neptune Chapter Two Video Discussion/@comment-4339150-20110824003320

i think the most interesting thing is that while the Tiber River washed away Percy's invincibility, it had no effect on Frank, Hazel, or the gorgons (upon contact). Percy had to smash to gorgons to get them to dissipate, where the River Styx 's water killed monsters/skeletons on contact.