Pherin were froglike in appearance and were about the same size as Humans. They had long, spindly limbs, with large knobbly joints. Their heads were wide and had two large eyes, which could move independently of each other. Along their abdomens, the pherin had a series of blue-green spots, which could produce a dim glow.
Like the lluma, a species of Nyriaanan grazing animal, the pherin were hermaphroditic. Each individual could assume either a male, female or neutral gender and at any one time, between ten and twenty percent of the population were neutral, with roughly equal numbers of males and females.
Pherins liked to attack in large numbers anything they saw as intimidating. Although they were generally peaceful, they would attack if provoked and sometimes utilized improvised weapons, such as stones. Male pherin were more likely to attack than female ones and neutrals could be particularly aggressive, if they felt that their family unit was being threatened. Threats to the pherin included Nyriaan's settlers, as well as the native chlovi cats, a type of dangerous predator.