Rockseeres dress very plainly in cloaks and garments which blend in with their surroundings, brown and gray being the favored colors. The garments are woven from tough fungal fibers, but such is their craftsmanship that they appear almost to be normal clothing. Treatment with plant extracts renders them waterproof. In contrast with this plain garb, they wear rich jewelry, usually of silver and always set with gems.
Society: The lairs of Rockseers are supremely well disguised and warded. Multiple spells are always cunningly placed to prevent other creatures even suspecting the existence of such a network of caverns and passages, let alone entering them. Spies (usually thieves melding lnto stone) are always placed to watch out over areas close to the entry points of caverns. Some Rockseers live in caverns accessible only by stone walking or similar magic, where hundreds of feet of solid rock separate them from the outside world, with only small fissures to provide air.
Rockseers are highly unusual among elves in that they have little curiosity. Few among them have any desire to learn the ways of other folk. This is largely the legacy of a long historical sense of shame at their mythic history; they consider themselves tainted and instinctively avoid those who they think would condemn them. Once awakened, however, their curiosity can lead them to act in uncharacteristic ways, as those who stumble upon them will soon discover.
Rockseers are gem cutters and craftsmen almost without equal and even gnomes and dwarves would hesitate to daim they could better Rockseer work.
Rockseers are strange, alien, and fey people even by the standards of elvenkind. They are a serious people with little of the light-hearted, frolicking, bantering ways of most elves. They speak their own dialect of Elvish. They also know fragments of Svifneblin, and most can speak pech. A few have a smattering of undercommon and can communicate with Derro or Duergar (not that they would wish to do so, but it is useful for intelligencegathering).
Ecology: Rockseers hardly interact with anyone else in the darklands and underdark. They eat fungi, moss, lichens, and cave creatures such as lizards and eels. They avoid violence and the endless struggle between different factions in the Darklands and keep to themselves. They are calm, enigmatic, and extraordinarily hard for outsiders to understand.
From the Advanced Players Guide: Pathfinder
-Earth Glide (su): Rockseers of at least 3rd level can Earth Glide once per day for a distance of 100 ft. + 100 ft./level gained after 3rd. This ability allows them to move (but not see) through stone as if it was air. At 9th level rockseers may bring 1 companion along with them plus 1 additional companion per level over 9th.
-Stone Sense (su): Rockseers intuitively know the direction, distance, and size of open spaces within range of their Earth Glide ability. This ability doesn’t tell the rockseer if the space has breatheable atmosphere or is already inhabited, it only tells the rockseer the shape and size of the space.