Black Marrows are named for their dark colored hides which are encased in a distinct exoskeleton. Their skull and the top edges of their spine push out from under the skin as they age. As such, their young need excessive amounts of calcium for this armor to develop. The older a Black Marrow dragon is, the more skeletal their appearance. They often use their skeletal looks to lure in foolish scavengers or terrify predators. These vicious dragons love nothing more than to crack open bones with their stony beaks and eat the marrow inside. Voracious scavengers, Black Marrows will swarm and devour corpses both old and fresh, sometimes even dragging larger finds to the water to allow them to “ripen.” Despite their dreadful demeanour and often horrid stench, Black Marrows are devoted mates and parents.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

All of the hatchlings at the cave used to be terrified of Rhythen, but one day when the hatchlings got lost in the woods he proved his worth.  The hatchlings ran into a bear and were backed up against a wall when it was about to attack them—that is, until Rhythen flew in and scared the bear off.  For once the hatchlings weren't scared of him and were actually thankful, running up to hug him in thanks.  Hearing this another Bone Marrow named Korra Onyx started to show interest in Rhythen, seeing him as a good dragon rather than just another dragon.  Everyone used to see Rhythen as scary but Korra didn't, and a while after the incident the two mated.  Whenever a new hatchling seemed afraid of Rhythen, Korra, whom looked more like a black dragon than a bone marrow would tell them about the incident with the bear and then whisper to them, "Beneath that tough exterior, he's really just a big softie".