The Isthul is a deadly race of Xaviliaxian worms that arose in the early years of the Second Era. There are a few variations of the Isthul worm, each specialized to the needs of the Swarm.
Every worm has it’s own nervous system with a simple brain, and a small cortex. While the simple brain handles things like movement, ancestral instincts, autonomic functions and homeostasis, the cortex has enough room to store a small amount of simple information (be it data, crude understanding, or a memory). By itself, a worm is pretty dumb, useless and squishable, but together they can achieve highly complex tasks well beyond what any one of them could have alone. They communicate with one another through a simple language of contact and synaptic connections.
Their survival is dependent on their ability to cooperate as one being, so they will often swarm into one large mass. This strategy is not relying on the strength in numbers instinct so much as it is enabling the swarm to meaningfully precieve the world around them, recognize problems, consider and decide what they need to do to improve and/or ensure their survival as a swarm, and act as a unified whole. In laymen’s terms, an Isthul swarm functions as a large, writhing brain. When the Swarm encounters a novel problem, the swarm will rearrange entire sections of itself to stimulate new synaptic connections, thereby enabling new ways to understand and address difficult problems. The more fierce the mass is writhing, the harder it is trying to solve a problem.
The Common Worm serves as a pool of information and comprises approximately 90% of the Swarm. Despite the name “Common” Worm, the Swarm often keeps these squishy members safely underground, creating a vast neural network that can stretch for miles. The other 10%, however, are specialized types of Worms, and serve the Swarm as eyes, defense, offense, and one unique type that can (afforded the opportunity) settle itself in another creature’s brain and use the body as an extension of the Swarm. At the discretion of the Swarm, this worm will either learn from this slave brain or wipe it to store the Swarm’s own amassed data (like a back-up). The former is often utilized to meaningfully communicate and act on behalf of the Swarm with the Auolean races (although many revile them, as they are an abhorrent sight to behold), while the later is often stored in a discrete location, devoted to the needs of the Swarm.