Source: Beyond the Veiled Past, pg(s). 90-91
The sea linnorm resembles a sea serpent with a distinctly draconic face. Its dark grey scales with swatches of crimson help it blend into its deep ocean habitat. Lures dangles off its face, each glowing with a pulsating orange light accented by regular electrical discharges. A typical sea linnorm grows up to 55 feet long and weighs around 14,000 pounds.
Sea linnorms power their lures and breath weapon with bioelectricity. This breath weapon is a powerful bolt that overwhelms the nervous system of living creatures in its path and is further empowered by the innate bioelectricity of victims, creating additional discharges that arc off the breath's straight trajectory toward the nearest living creature. This breath weapon is capable of overwhelming entire schools of fish at once when the sea linnorm hunts.
After eating, a sea linnorm hibernates up to centuries, long enough for entire aquatic settlements to emerge. Inevitably incurring the wrath of the beasts, some of these settlements adjust their entire societies to provide for them, shepherding schools of fish toward their lairs and, in harder times, encouraging visitors there.
It is believed that sea linnorms are effectively immortal, with the oldest recorded ones surviving well over 5,000 years. Their death curse causes their killer to feel the pressure of crushing depths when fully submerged in any water, regardless of depth.
Sea linnorms live in the deepest oceanic trenches and rarely surface, usually being already sustained by the schools of megafauna in their habitats. Due to their voracious appetites, a sea linnorm's perceived territory encompasses a space of several thousand square miles. Any intruder considered to be a threat is sought out by the sea linnorm who recognises that it will either triumph or die: better to die in the open water than be cornered in its lair. Settlements inside their territory are used as warning systems, being seeded with traditions of alerting the linnorm to the presence of potentially threatening outsiders or of certain apex predators like krakens or luscas.