The Selyoids were beings of pure light.
Selyoids were originally beings of light, but climate change caused their scientists to devise a corporeal form. Their corporeal form was a primordial soup capable of travelling through space on an asteroid.
On their own planet, the Selyoids lived purely to express their creativity, as a race of artists. Their scientists were outcasts.
BEHIND THE SCENES
The name of the Selyoid obviously derives from celluloid, a chemical used at one time in the production of film stock