Scream of the Shalka 4.Bölüm Doctor Who - Anime

The Shalka appear to be a serpentine alien race made of living rock and magma, but they are actually bioplasmic entities, living plasma, their physical appearance merely a "crust" concealing their true forms. They breathe volcanic air and prefer high temperatures, being most comfortable underground where lava meets metamorphic rock. They communicate through high-pitched screaming, which they can use for a variety of effects, like tunneling through rock or mentally controlling other life forms. They also use sound as a part of their technology.