Strang was a Sontaran whose genetic makeup comprised an entire Sontaran clone batch.
Due to his exposure to a certain compound, his body was altered without any alteration of his appearance or biological functions. He gained an indestructible and impenetrable anatomy. His skin was impenetrable making it a virtually indestructible and resilient armour. Despite its virtually limitless resilience and indestructible structure of his tissues, his skin did not lose any elasticity or sense of touch. He could not be even be harmed via his probic vent. (AUDIO: The King of Sontar)