Most Vaathkree are about human size. They are seemingly made out of stone or metal. Vaathkree have an unusual metabolism and can manufacture extremely hard compounds, which then form small scales or plates on the outside of the skin, providing durable body armor. In effect, they are encased in living metal or stone. These amiable aliens wear a minimum of clothing, normally limited to belts or pouches to carry goods.

Vaathkree are long-lived compared to many other species, with their natural life span averaging 300 to 500 Standard years. They have a multi-staged life cycle and begin their lives as "Stonesingers": small nodes of living metal that inhabit the deep crevasses in the surface of Vaathkree. They are mobile, though they have no cognitive abilities at this age. They "roam" the lava flats at night, absorbing lava and bits of stone, which are incorporated into their body structure. After about nine years, the Stonesinger begins to develop some rudimentary thought processes (at this point, the Stonesinger has normally grown to be about 1 meter tall, but still has a fluid, almost shapeless, body structure).

The Stonesinger takes a full two decades to evolve into a mature Vaathkree. During this time, the evolving alien must pick a "permanent form." The alien decides on a form and must concentrate on retaining that form. Eventually, the growing Vaathkree finds that he is no longer capable ot altering his form, so thus it is very important that the maturing Vaathkree choose a form he finds pleasing. As the Vaathkree have been active members of the Republic for many millennia and most alien species are roughly humanoid in form, many Vaathkree select a humanoid adult form. Others choose forms to suit their professions.

The Deal - the code of trade and barter that all Vaathkree live by - is taught to the Stonesingers as soon as their cognitive abilities have begun to form. The concepts of supply and demand, sales technique, and (most importantly) haggling are so deeply ingrained in the consciousness of the Vaathkree that the idea of not passing these ideas and beliefs on to their young is simply unthinkable.