Ovipares

Ovipares are egg-laying creatures. Which, in the world of Cridhenan, have some significant differences when compared to mammals. Oviparous animals are entirely made of bones. Their body structures function similarly to crabs or lobsters, with their muscles and veins inside of the bones, like the chitin on a crab. Flexible but tough cartilaginous joints attach like tubes to the outside of bones. Types of bones vary from the milk white common on Earth, to char black, crystalline, filigree, spiny, etc.

Aquatic animals like fish, octopuses, sharks, stingrays, etc, have hollow cavities in their cores (different depending on the animal) with a balloon-like muscle (swim bladder) that they keep inflated to regulate their depth, and can change the inflation to rise or sink accordingly. When a marine animal dies, its swim bladder slowly deflates and their bones sink to the bottom of the seas or rivers, making river banks and lake bottoms prime places to salvage large amounts of ossein.

Because of their literal exoskeletons, they have very few natural predators. There are a few animals that have excessively strong jaws and don’t need to eat as often as others, so the effort and energy expended in hunting bony creatures is made worth it. However, most animals hunt mammals, or are herbivores. Because of this, the wild places on Cridhenan are filled with bony creatures, which is what makes ossein so naturally abundant in this world. When a creature dies, there isn’t much for scavengers to pick apart, so the bones stay there.