The Shadelings are globs of animated, organic goo. They have so far only ever been encountered in the shadow scars of Celenia. They seem vaguely sentient and seek out sustenance near to them by sliding, somewhat like snails, toward organic matter that they can break down and consume.
How these Shadelings are first formed is something of a mystery, but it is speculated that Shade, the energy of the Shadow Realm, when deposited in large amounts in Dunia will rapidly consume and corrupt the matter it is in contact with and eventually form a Shadeling.
This appears to only happen in areas where the Veil between the worlds is very thin and concentrations of Shade is high, such as the shadow scars. Peculiarly, they've never been encountered by any expeditions into the Shadow Realm itself. It is unknown if this is because they can only exist in Dunia, due to some complex interaction between light and dark matter, or because they exist in locations unknown in the Shadow Realm.
If Shadeling is left to its own devices for too long, it will grow as it feeds on its surroundings. Eventually it will become more complex, growing eyes that seem to almost float across its slimy surface. While technically still a Shadeling, these monstrosities are commonly referred to as Black Oozes or Oozelings.
It is not known of Oozelings will evolve into yet another form if left to their own devices, as no greater form of Oozeling has ever been encountered.
Unknown. They don't seem to procreate. Sensory details
Shadelings seem to have great senses with which to detect organic matter. They seem drawn to living matter in some way. How they do this is unknown as they lack any visible eyes, ears or even noses. Oozelings on the other hand have rudimentary eyes with which they perceive their environment. They retain the Shadeling's superior senses for detecting organic matter.