Even if the Heroic-King is always a High Jurakin, the real mastermind behind everything is the Tide-Tyrant: a sort of extreme intelligent and manipulator aquatic creature who can live thousand of years. The most prestigious Arcanists claims that Tide Tyrants are the aquatic cousins of Tyrant-Eyes, found in the depths of the earth.
Other legends says that a Tide-Tyrant is born once every few hundred years from a black Jurakin egg in unknown circumstances. This large aberration is capable to control the mind of other creatures, and provide them mutations and lesser mind powers. A Jurakin king is always provided of pecular mutations by the Tide-Tyrant. Expert says that when the King is mounting the Tide-Tyrant to lead his troops in battle, it is in fact the monstrous aberration who's controlling the mind of the Jurakin king to impress and inspire his troops.
This model has been hollowed to save you money. It does not need to be solid for durability reasons -- please inquire if this is of interest to you.