Shalka

The Shalka were an alien race encountered by the Doctor. They are made almost entirely out of lava and had no set form. The ones shown were large worm-like creatures with cobra-like frills, but there were also Shalka of different sizes and shapes.

They lived underground, near where lava meets metamorphic rock. They communicated by screaming, and breathed volcanic air; the only exception was Prime, the Shalka leader, who was able to speak and breathe oxygen. They used sound as a weapon and a means of controlling "lower alien creatures" and to accomplish other tasks. (WC: Scream of the Shalka)

Behind the Scenes
As the version of the Doctor who fought the Shalka does not exist in established canon, the Shalka themselves may not either.