Yldduc are entities that are around four feet tall, spherical, oval, loaf-shaped or egg-shaped creatures with cat-like ears, covered in thick, fluffy fur with the number of eyes varying between individuals. They have no skeletal structure and are capable of rapidly altering their physiology to suit their needs, interacting with objects via fur covered tentacles and move primarily by growing dozens of stubby, fuzzy legs covered in hooked hairs. They are incredibly fast and highly adaptable. Their fur is so thick it is seemingly endless and protects them from harm as it is virtually indestructible. Breathing for these creatures is an involuntary action to keep their form in a stable state and indicator of emotional state, as opposed to a need for oxygen.
A group of Yldduc is called a bundle.
The Yldduc are a sentient, telepathic race that form symbiotic relationships with other beings. By mimicing a local or similarly harmless entity, they entice others to form an emotional attachment to it in order for it to generate the energy it needs to maintain itself. This energy can be gained from friendship, romantic relationships or general acceptance by a community or society. They do not need physical food, but will accept food or participate in mealtimes as a bonding activity and can give themselves a sense of taste.
Yldduc are capable of creating objects to use as gifts, everything from money to textiles and even food. This consumes energy and can make them sick if they do it for an extended period of time. They cannot make anything larger than themselves and must be familiar with the object in order to make it.
They will seek out civilizations in a period of peace, mimic the general body shape of the local populace and attempt to find a place in said society, though they can also take on the form of animals kept as pets. Anything the locals recognize as alive, harmless and is a common sight in their society are the parameters the Yldduc use for the forms they take.