Selyoid

The Selyoids were beings of pure light.

Biology
Seyloids 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. (PDA: Dying in the Sun)

Culture
On their own planet, the Seyloids lived purely to express their creativity, as a race of artists. Their scientists were outcasts. (PDA: Dying in the Sun)

History
The Seyloids once invaded Los Angeles and somehow changed various movies, including The Time Machine. The Second Doctor, Ben and Polly stopped them. (PDA: Dying in the Sun, Synthespians™)

Behind the scenes

 * The name of the Selyoid obviously derives from celluloid, a chemical made in the production of film stock.