Species
This is just going to be me regurgitating what I know about the original series into this webpage, so take into mind that none of this content is original. Except the drawings, I made those. Anyways, the world is inhabited by a very small amount of wildlife, and three smart races at odds with each other.
Gems
The main characters of the story both here and in canon, on land one can find these organisms. Gems are humanoid minerals usually about 5 or so feet tall, and they're entirely solid stone. They can move and speak and have personalities because of tiny microorganisms which make their homes inside of their bodies, photosynthesize, and release that energy to let the body move. The microorganisms also hold their personalities and memories. They don't age, eat, feel pain or reproduce. They can be broken down into pieces and reassembled, but if they lose any body parts and have them replaced, they will lose some memories. Every couple of centuries, a new one will emerge from the ground, though most of the time they won't have enough microorganisms to become autonomous and will instead be scrapped for parts. They come out of the ground looking raw and jagged, but can be polished into shape. They're typically named after whatever mineral makes up their body.
Lunarians
The six moons of the world are inhabited, too, by the wandering spirits of humans who died on earth a long time ago. Also known as the moon-people, they come down to earth to hunt the gems and take them back to the moon, and are also in control of most of the admirabilis population. They get dressed up when they come to earth and are completely silent, but behave like normal humans when they're back home on the moon. (Or... moons?) They do not reproduce or die, though each of them are many many years old and very tired. They have strong food, architecture and fashion cultures. If they're injured, they explode into a cloud of dust and regenerate back on the moon. They have access to all sorts of advanced technologies. They're typically named after plants or insects.
Admirabilis
In the sea, one can find people called the Admirabilis. They're mortals who live about 20 years, reproduce sexually, and consume corals or other invertebrates found in the sea. In canon, they experienced a great famine and were almost all taken to the moon, becoming cattle in exchange for being fed. On the moon they can grow very large, on earth they tend to be small. They have two forms that they use: a small snail-like form with a shell, and a larger humanoid form without a shell that they can turn into when they're close to their home. They have long, latin-based names that often end with "-us".
Invertebrates
A decent population of invertebrates (insects, crustaceans, molluscs, so on) exist in the world at this point. Some of them are used as resources, like some butterflies whose intestines are used as bleach, but most of them are let be.
Small Rocks
Finally, some rocks get to be sentient even if they aren't gems. These guys operate on different physiologies than the rest of the critters that inhabit the world, but because of that they can't be understood by any of them. For now, they just sit silently.