To prevent the catastrophic cosmic collapse of a dying star, the most powerful interdimensional wizards gathered on a fragile planet to summon Ghrolthakon - The Eater of Stars.
They built an immense stone tower that reached from the planet's crust and into the empty void of space. At the top of the tower, they performed a thousand year ritual to build a dimensional prison around the star.
When they finished, they offered up the disintegrating planet as a sacrifice to Ghrolthakon. Ghrolthakon swam through the black sea of space and devoured the dying star.
Ghrolthakon swims between worlds, in the boiling seas of newborn planets, through the gaseous hearts of red giants. Her brood falls through invisible chasms of space and time and into known and unknown worlds where they grew into silver-skinned collosi that swam beneath the waves or giants of mud and rock that writhed within the fiery chambers of the earth.
The sea-born and the two-legged beasts of the woods came to know them, and together they made pacts and sacred covenants with those of Ghrolthakon's kindred - among them were the Atalacamani - the sea-born women who would change their shape to walk among creatures both foul and fair. Ghrolthakon's eldest daughter Abakhatan is their queen and she swims in an ancient ocean of primordial blood at the core of the world.
The Atalacamani are a dark reflection of the selkies and sirens that have vexed sailors for centuries. They are the cousins of the horrible pennangalan, naga, and sigbin of Asiatic folklore, the foul and infamous legendarium of the Plateau of Leng, and of the shape-changing Buryat of Olhonsk who offered sacrifices to their hostess of the sea. Secret cults of men worshipped the Atalacamani by flagellating themselves with seaweed and finally castrating themselves, delivering their blood and genitals to the hungry sea.