I am writing a story, and it takes place in a solar system way far off from our own. One of the planets, Veynerth, is a dry, deserty planet, but in certain areas there is high volcanic activity. However, the species that live on this planet and have mostly civilized it actually live inside of dormant volcanoes and the areas around it. I don't know if that would really be possible, and I have been trying to make it seem more plausible. The one thing that helps is that it's sci-fi, and we don't even know what type of worlds are out there, so there's some room for unexplained things.
The "aliens" are much like humans. They have thicker eyelashes to protect their eyes from falling ash, etc. but their hair is also thicker. Their skin is dry and some areas are almost scaley. Their eyes are adapted to see in dark conditions. Some help with the features and how the species SHOULD be would also be helpful.