WORLD : PRIMORDIALS
Primordials were the first living beings that spawned on Nym, before the Aithereals anchored Ai-Thera to it. They were gargantuan creatures who moved seas and mountains; shaping Nym into continents and oceans. They were born from the magical energies of the Worldsea, and inherited purpose and memory from the Worldshard.
However, most Primordials were similar to Celestials; not entirely intelligent. If anything, they were more like animals and were driven more by instinct than sentient thoughts. When Ai-Thera was anchored to Nym, the Aithereals began to interact with Primordials, sometimes by merging with their souls.
In ancient times there were many Primordials, such as the abyss-dwelling seawyrms and the mountain-shaping stonegaerm. But most were killed during the War of Titans by the Elemental Titans, and those who survived went into hiding or evolved to become ancient beasts, or merged with the very land itself. Seawyrms in particular still roam the deepest abysses of the seas, though sightings of them on the surface are so rare that anyone doubts that sailors ever see them, blaming their sightings to sea-sickness or alcohol.
Other, more intelligent Primordials evolved to become Earthen Gods or Wildgods.
Sea Mothers
Three Primordials were particularly powerful during the ancient times. They were known as the Sea Mothers, and were the ones who breathed life into the seas.
There was Claxul, the Shellmother, Slaa, the Wyrmother, and Zael'shi, the Turtlemother. Come the War of Titans, the Sea Mothers fought the Elemental Titans and only Zael'shi survived. Slaa's body was used by the Creators' Dragonforgers to help shape the first Dragons, whilst Claxul's body was never recovered as it sank into the darkness of the Abyssal Depths.
In zjindri cultures, the Sea Mothers are still worshipped as gods, and it is a tradition and faith likely adapted from the sarazhi before them. It is thought that the spirits of the Sea Mothers still live on through the Ebb and the waves of the Worldsea, and sightings of Zael'shi have been reported not only by zjindri priests, but by some sailors in general. A phenomenon known as a Zael'zjahna (Zael'shi's Wake), where hundreds of glittering sea turtles swim together in the open sea, is said to be evidence of Zael'shi's recent resurfacing from the depths. A Zael'zjahna is generally considered good luck, so long as one doesn't disturb the wake.
Korr
Supposedly the first Primordial. According to legends he grew so large that he fell into the Worldsea, shattered and became the lands and continents of the world, and from him spawned the other, smaller Primordials. It is an entertaining idea, but it is considered to be a tribal story, often told by primitive tribes as tales for their children.
It is, however, a strange occurrence that the tale repeats itself across so many tribal cultures, in each a different corner of the world. It is likely that a being known as Korr did in fact exist, but to what extent one can't truly say. The origin of the stories are lost in time, as they all began as oral tales to begin with.
The Worldwyrm
According to Sifiran legend, the Crown of the World actually sits on the back of a gigantic Primordial wyrm, that connects the continents of Aesudarh and Norne. Sifir and her sisters faced him on their way to the Worldthrone to fight the Elemental King Teruk, and a prolonged battle led to a retreat by Sifir's sisters, but Sifir herself prevailed and defeated the Worldwyrm.
Her blows couldn't kill him, but instead she managed to trap him beneath the ice and put him into a deep slumber. After claiming the Harrowfrost from Teruk, Sifir used it to cover the rest of the Crown of the World in ice to keep the Worldwyrm in its deep sleep. It is said that Sifir sings a song to calm the Worldwyrm as it slumbers, and it is supposedly evident when the Crown of the World shakes and settles briefly afterwards. Sifir also taught the Skaldur giants her songs.
Sifir expects the Worldwyrm might awaken again and seek her out; bringing destruction to the northern continents when he does. The Golden Legions of Aesgarn prepare for that day, and it is prophesied as the End Times when the Worldwyrm will consume the Harrowfrost for itself and swallow the entire world with it. It is believed the creation of the Sifiran Pantheon was for the exact purpose to stop it.