Seal Tortoise pets are similar to the other Non-evolvable pets in the sense they start from level 60 and have no skills. They will also take up a pet slot, have loyalty, and can be ridden. They are obtainable from the Seal Turtle Lucky Box.
Like Unicorns, the Seal Tortoise can "evolve" to become a True Seal Tortoise and an Ultimate Seal Tortoise. True Seal Tortoise require two level 65 Seal Tortoise while Ultimate Seal Tortoise require two level 70 True Seal Tortoise. The primary difference is in their appearance, where they will sprout armor and begin to glow. You will need the True and Ultimate Seal Tortoise Alchemy Scrolls from the Item mall to do this, based on their respective kind. Actual Alchemy or High level alchemy is not required for this.