Strang was a Sontaran whose genetic makeup comprised an entire Sontaran clone batch.
Due to exposure to certain compound, his body was altered without any alteration his appearance or biological functions. He gained an indestructible and impenetrable anatomy, his skin was impenetrable making it a virtually indestructible and resilient armor, however it still retained its elasticity. He could not be even be harmed via his probic vent. (AUDIO: The King of Sontar)