Rosemary describes the Quelin as "lobster centaurs". They are a blue arthropodic species with many legs, mask-like faces, and flat, black eyes. They have thick, black-blue domes on the top of their head they can use as rams. They often decorate their shells with symbols and polished stones. Although they are a part of the Galactic Commons, it is rare for a Quelin to travel outside of their own space, as they are a particularly xenophobic species.
Quelin are often a harsh and bureaucratic species. They have strict laws against inter-species relationships and cloning. Cloning is seen as especially evil because of a series of Quelin wars involving eugenics and cloning. Artis Corbin, a crew member on the Wayfarer, was discovered to be a clone and was treated violently while a prisoner of the Quelins. Teracite ore, used to create circuit panels and other tech on ships, is mined in penal colonies by Quelin prisoners.