You have to pity the poor plesiosaurus. It used to be that, even in the most dinosaur-phobic campaign, the plesiosaurus had a place, hanging out in fantasy Loch Ness or the Underdark. But now we have the water orm, and the plesiosaurus is back in the dinosaur ghetto.
Richard Pett covers water orms in Mystery Monsters Revisited—their appearance varies, they are equal parts highly curious and legendarily elusive, and the stories told about them grow with the telling. (Though maybe this is deserved, since unique versions of the creature seem to manifest magical powers even beyond the ability to melt into water.) Everyone in the area will have an opinion about the water orm, even when no one can provide an eyewitness account.
A dam built during a dry summer traps a water orm far downstream from her winter nesting grounds. As the slope is too high for her flippered form to scale, the frustrated orm is growing violent in her desire to return home.
Grandfather Scales has a reputation as a fearsome, elusive beast and, paradoxically, as a defender of children—a fact slavers, crusaders, and orc hordes have all found out when they have tried to wrangle innocents across the bridge over the water orm’s lair. But Grandfather Scales is only so perceptive. Sometimes the “children” he defends are halfling rogues, spriggans in gnome form, attic whisperers, and worse.
A magical bottle purports to hold a marid—its side is emblazoned with a laughing genie riding a wave. In reality, the water in the vessel is the dissolved form of a water orm. If the command word is spoken, the genie on the bottle will indeed have something to laugh about, as the wielder will have to contend with a very irate river serpent in very close proximity.
—Pathfinder Bestiary 2 280
Edit: Checking one more late entry off the list. Thanks to filbypott and cobaltwashere for the kind thoughts. Original post (and original edit to that post): Still at memorial service. Thanks for your patience!
Edit: I’m back from the memorial service but need to take this week off due to a personal matter. Rather than risk more placeholder posts, I’d rather pause this week, focus on that and get caught up on some of my back posts.