The Pryllgu is a Kryptonian sea-monster.
This huge green scaled creature has wide side mounted eyes and a large bulbous structure on top of its short snout. Fangs larger than a man are also discernible. It has the mass and strength to lift the two-masted schooner 3-Val out of the water.
Most of the Pryllgu's body remains below water, so it is unclear whether it is of a serpentine, whale, or plesiosaur type form.