The creature seems to be a mutated corpse that is covered in grey skin tissue. Perhaps the human subject was dead before it transform into this monstrosity. It's eyes are glowing white meaning the mutation must have change it's pupils allowing it to have somesort of night vision.
The creature may look weak due to the unmassive muscle mass but is suprisngly strong. Speculations have conducted that the muscles were tightened to give it an advantage in strenght. It's bloated stomach contains green stomach acids that the creature can use against it's prey or explode emmiting it upon death.