Turritopsis Dohrnii; Immortal

The immortal jellyfish can potentially live forever, no?

Sea creatures lived like.. sea creatures. Suddenly, some strange mutation seemed to happen to many of these sea creatures. Over decades, they slowly developed into.. humans? Underwater humans? Humanoid sea creatures, whatever you want to call them. But you know how humans are. Greedy. Power hungry. They'd do anything just for serotonin and dopamine.