Clansmen were more of an organization than a species, as Chiana, a Nebari, joined them temporarily when she believed her brother Nerri to be dead. The majority of the Clansmen did appear to be the same species; an unnamed species that greatly resembled Sebaceans, except for their very pale eyes.
The Clansmen were a group of tribes who lived in caves below the gravesites on a Royal Cemetery Planet. The cancer-causing radiation from the caves generally killed them before the age of 22 cycles. Parts of their group, the "Lost People," were members past the age of 22 who began to show the effects of radiation; these "lost people" never "took the stone." When babies were born, the older members (around 22 cycles) "took the stone" which was to jump from a cliff into a sonic net, which could cushion their fall or could let them die from the impact.
Whether because of the radiation in the caves, the toxic hallucinogenic mushrooms they ingested, or one of their many other mind-altering pastimes, all of the Clansmen seemed to be a little nutty. Because they rarely survived past 22 cycles, anyone older than that (such as Aeryn Sun) was considered "ancient" and "historical," an amusing but somewhat disturbing concept. All of the Clansmen dyed their hair reddish-orange, leaving spare drips to stain their foreheads, and moved in a similar shambling shuffle that resembles the movement of something dead rather than alive. An interesting physical trait was the female's transparent abdomen during pregnancy, caused either by their species' genetics or the influence of their environment, which allowed a view of the developing fetus.