They live in the tundra and as such have developed thin legs for wandering about in the snow, a great deal of fat to keep warm with many folds to tuck their extremities into. They're very social and lack just about any natural predators, so presumably make up fairly large communities that I can only assume sleep in massive piles like they were the worlds ugliest croquembouche.

Goblins in Wayfaring Strangers universe are a race with highly variable genetics, potentially making even just three or four generations of breeding vastly different from the original parents. It's a double edged sword, though, and while it makes it very easy for them to adapt to an environment, it also causes a great deal of unwanted features, like incredibly stubby arms, no feet, tens of fingers, unusable jaws, etc., that may or may not cause them to die off very quickly. Not all of the features they evolve necessarily let the rest of their biology catch up, causing issues like high percentages of premature births in larger breeds of goblins.

While goblin physical features are often very different, their mental features are largely the same which is also somewhat double edged. On the upside, many goblins have a knack for picking up languages and are able to quickly deduce the language and vocal mannerisms of any goblin from any place. Language of other races are a bit more difficult, but will often be picked up much faster than a person of that race. On the downside, they're mostly stupid and have basically no foresight, so they're not good problem solvers. Most inventions they have fail miserably, often killing the individuals testing it, and are never written down in case the inventor does die, so there's not a lot of cultural or technological mobility.