The Sontila are a sapient race native to the planet Sonti, orbiting a binary star system.
They're an arthropod-like species and shed their old shells as they grow too big for them. The smaller Sontila take up the shells left behind by their larger ones so they can grow inside them, much like hermit crabs.
They use salt as currency. Their culture includes comic books, depicting the adventures of heroes such as the Splendid Sandhopper.
- Big Finish Doctor Who audio releases - Short Trips: Volume 2 (2011) - "The Doctor's Coat", by John Bromley.