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. Despite its virtually limitless resilience and indestrutible 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)