Planet of origin: An unknown plant in Galaxy 4.
Rills are a sentient ammonia-breathing species which developed an advanced pacific spacefaring civilisation with intergalactic capacities.
They are large, scaly sexuate creatures with massive skulls, wide mouths and large eyes. They rely on their telepahtic abilities to communicate, being unable to do so verbally. Tey have very long liespan and a slower perception of time than most species. It remains unclear if this is their natural state of being or if this came about after genetical manipulations they went thru in order to increase their original lifespan. It takes them a thousand years ot mature and their normal reaction time is fifty times slower than a human. In order to deal with other species, they are able to increase their reaction time for short periods but find this practice unstelling. Solitary beings, they prefer to spend most of their time thinking, leaving physcial tasks and interaction with others to robots called Chumblies.
Source: Doctor Who universe, Galaxy 4