Appearance. Feared beings of
the Web. Without physical form, spyders
appear as nothing but wisps of mist or ghostly shadows to those without the
magic sight that Weavers possess after the
Ceremony. The Weavers can see them because
they, like the Web, are composed totally of
magic. To the Weavers, while using their
sight, they appear as hideous, monstrous creatures
with up to twelve appendages, but whether they are
arms, legs, wings, tails, whatever, is unknown.
As far as is known Spyders have no eyes, for they are
believed to sense their surroundings with magic means only.
They do not have ears or mouths, most likely for the same reason, and
communicate by using their magic. This manifests itself with those who inhabit
Caelereth as telepathy.
Special Abilities. The only real ability spyders have, which is known, is that they can possess creatures. That, and their ability to steal magic and knowledge, make them dangerous. Although they have not been known to actually hurt anyone, with a few cases of forcing those they possess to commit suicide. Still, they cannot be killed, and can still potentially kill, which makes them a great threat to Weavers, even today, although they are not as numerous as before.
Territory. Spyders tend to stay in the "land" to which they are native, the strange pseudo-world known only to the Weavers, named the Web. Since the discovery of the Web they have been known to come into Caelereth, but these occasions are rare. It is also unclear if and how they can survive for longer periods of time in such a world, which is very different to their magical one.
Habitat/Behaviour. However, it seems that the Spyders which enter Caelereth are attracted to those who hold powerful magic. They delve deep into the person and attach themselves. While in the person they take any knowledge they think would be profitable, as well as what magic energy they can. This is the same for those unlucky Weavers who meet one in the Web. Some Spyders have also been believed to be scouts of some sort. They would possess a Weaver and take only his knowledge. The Weavers discovered that in order to get rid of a Spyder they only need to dispel magic, which is all the Spyders are. But even when dispelled the Spyders are not destroyed, only sent back to the Web from where they originiated. Still no-one knows how to destroy them.
Diet. Some Weavers think that the Spyders feed on magic, for that is what attracts them to a person. To take the magic from a person, or to feast, they possess the person's body and take it from the inside. Whether this is for food, or for some other purpose, however, is still unknown, as is much about spyders.
Mating. The mating again returns to the magic that they take from people, seemingly as a means of eating. Others believe that it is, in fact, to create more Spyders. Since Spyders are composed of magic, it is very likely that the Spyders use magic to create new ones. Still, this is unproven, and unknown as of yet.
Myth/Lore. The only (known) relative of this creature is the Mystran. It is believed that many years ago, when the Spyders were trying to find every way they could to get into Caelereth that the Weavers didn't know about, they went through different worlds that might possibly have ways into it. It is likely that they came upon a shadowy one, where evil seemed to be natural. Just as they were about to turn back they found a portal which opened into Caelereth. Those Spyders who went in through the portal found themselves stuck in their shadowy forms, and changed. The evil from the realm they had been in stayed with them and corrupted them. This created a being which is now known as the Mystran (at least this is one of many theories). However, it is a fact that Mystrans are now deeply hated by Spyders. The opening to the shadow realm from the Web has long since been closed by the Old Weavers, but the Spyders will always remember to be careful when entering new worlds.
Furthermore whispers pass among the Weavers about the nature of the Spyders. Weavers ask themselves about their creation, what they do, how they came to the Web, if they are the minions of some powerful God who uses the Web as a dwelling etc. - and most answers still aren't found. One of the most popular rumours is one about how Spyders created magic. It's somewhat of a myth, although it is but whispers among people: They say that, at first, there was no magic, and only Spyders in their empty dimension. The Spyders became confused and angry, and in the fray which followed, one died. It was ripped open and out from it spilled all that is now known as magic, and the Web. From the entrails and blood, or magic, which came forth the Spyders began to spin the Web into what it was when the Weavers found it, a powerful source of magic which reached into all worlds. A strange story as it seems, which of course is quite unlikely to be ever proven, but nevertheless one which is very common among the Weavers.
Note: All information in these categories are taken from the book "Mysteries and Myths of The Web" by Ef-Skot Fitz Jrald and are not proven as the truth, only the popular belief.
Information provided by Tarquet Galbar