The Nautuli are a race of trans-oceanic amphibians that underwent a metamorphosis around 600 years prior to Phantasmagia. Originally exclusively aquatic, they developed the ability to survive terresterialy.
The Nautuli had little to no communication with the rest of Phantasmagia for millennia. As the waters were always considered even more horrifying than the already generally accepted level of horror, exploration was always kept to a bare minimum.
Approximately 600 years ago, there was a mass evolutionary exodus out of the seas. This event was called "The Great Surfacing". Their history prior to this event was lost entirely in an undersea cataclysm. The nature of this disaster & if it catalyzed their emergence, is a closely guarded cultural secret.
The Nautuli are extremely diverse physiologically as they developed in various different marine environments. They appear to be a jumbled genetic mixture of the taxonomic classes Cephalopoda, Crustacea, Chondrichthyes & Gastropoda, to name just a few.
Though almost all Nautuli spend their lives on dry land, all are still entirely capable of breathing underwater. Additionally, Nautuli can access the genetic memory of their ancestor's original oceanic forms. These forms can range from simple swimming fish to monstrous leviathans. This metamorphosis is temporary & physically strenuous to undergo.