Cassandra
Cassandra is a large moon orbiting a gas giant named Ouranos. It orbits a K class star inside it's habitable zone. It was created by a god named Cinder, who didn't realize it was condusive to live and was thus left abandoned for hundreds of millions of years.
Cassandra is one of four large moons, and is the second in orbit from its planet. Like all other large moons, it's tidally locked. Only one side of it ever faces Ouranos. A single orbit takes around 35 hours. The two other moons that orbit closest to Cassandra exert tidal forces on it, creating something akin to the tides on earth as well as causing significant volcanic activity. The sulfur expelled by these volcanoes is a definite threat to Cassandra's already stressed ecosystem.
Millions of years after natural life evolved, Cinder returned. Sapient life hadn't evolved, so she decided to make her own in the form of humans. For eons they lived alongside each other until another god named Daksari discovered Cassandra and locked Cinder inside of it for committing the sin of interacting with mortal beings.
Fauna
The naturally evolved fauna of Cassandra follow a hexapodal body plan, meaning instead of four limbs as on Earth they have six. Similar to Earth, hexapods evolved from a single ancestor that over millions of years evolved to be superficially similar to many of earth's modern day animals like canines, felines, ungulates and more.
Extremely old gif I made of the hexapod ancestor
One of Cassanra's largest predators are the pesagi. Evolved from a basal ancestor to modern pseudoequids, these are large, carnivorous flying animals. Most will only attack humans if they feel threatened, but to Cassandra's wildlife they are deadly. Pegasi can range from 7 1/2 feet at the withers to only 2 feet.
One of the most common animals in Promethea is the horse. True wild horses aren't native to Promethea, but were instead brought by settlers centuries ago when the invasion and occupation began. Their relatives however, the unicorns and wild mountain horses have lived in Promethea for hundreds of thousands of years and lived alongside early humans (after extinction event)
Domestic horses and sheephorses are kept for riding, meat, fur, and leather. Plains unicorns (larger herding species) are wild and oftentimes dangerous, but are also hunted for meat by certain nomadic clans.
Two keystone species of Promethea's ecosystem are the plains wolf and tree dog. Plains wolves are widespread in the southern steppe and hunt plains unicorns in packs, while treedogs are solitary hunters. Tree dogs claim massive territories and will attack any intruder, but most are timid and flee from humans.
