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The snoods are a race of hardy red-shelled humanoids with fleshy chin sacs. They most often live in caves, dungeons, and anywhere else a plucky group of adventurers might force their way into, kill everything they see, and ransack for valuables. The snoods aren't there to protect anything, that's just where they live. They're technically giant eusocial bugs, but you don't need to worry about that part.
A lot of this will be pretty vague, because I decide canon in small bits and pieces.
Snoods are humanoids with red carapaces and a fleshy protuberance on their chin.1 They stand somewhat shorter than humans, with thin limbs attached to a round body. The underbite isn't something they all have, that's just a stylistic thing.
Snood reproduction begins much the same as most eusocial insects. A queen2 gets knocked up and starts laying a bunch of eggs. Baby snoods hatch from these eggs as snoodlings. Snoodlings are cared for by immature queens, who prepare them for whatever job they will need to perform. This takes anywhere between 2-6 years (Maybe. I'm undecided.) and has an effect on how they mature, into a fully-grown snood. If for some reason a snood is not prepared properly, if at all, thay will not be able to properly mature and their growth will be stunted, appearing as a snoodling for the remainder of their life.
An immature queen3 is one of the things a snood can mature into, which can eventually mature even further into a snood queen. Snood queens cannot move, and have a continuously increasing caloric intake as they grow larger and older. Snood queens age like lobsters, which is to say that instead of aging they simply grow larger, requiring more and more calories until it dies of starvation, sickness, or is otherwise killed. They don't do much besides eat and lay eggs. Being the only stage of a snood's life that can make more snoods, they are very important.
If a snood is not an immature queen, but instead something like a builder, hunter, gatherer, etc., they'll probably die at like 30 or 40.
Most commonly, snoods make their habitats in large, mysterious dungeons. However, snoods have also been known to colonize abandoned buildings, ancient ruins, underground tunnels, and other thematically similar locales. Because of this, a snood will likely live the entirety of their life indoors.4 While snoods sometimes build structures, they rarely create tunnels and are generally are not known to create their habitats in favor of colonizing pre-existing seemingly uninhabited locations. Despite their preference for habitats that aren't being used, it is sometimes possible for two colonies to unknowingly settle themselves in the same general area. This will be covered in the following section.