An old legend shared by many is the legend of "Wublins" supposed monsters from another multiverse, it's said that some of these "Wublins" creeped out from their universe and made it to this one. The Picrowm is one of such monsters, and once it escaped it evolved to have grown more aquatic characteristics over time. Some say once it left it's original universe it found itself straight in the sea, however that's still up to speculation. @Lonrad for Shellk