Cat Seal

You can acquire one by starting a new game and only taking blue bonus professions and traits. They also very rarely show up in water portals and can be captured like any other creature. They have a special trait that gives you an extra choice in Essence Portals. There is also an event that can trigger while dating on the beach that implies you will take one home with you, but it appears to be bugged and the seal and that event never show up again.