Thread:Arawn 999/@comment-38818520-20190809181317/@comment-25192437-20190810202827

Not all of them. Knull's exact words in that section were "I was... unrefined in those early days. And as such, the creation of the Proto-Symbiote was... unclean. To this day, the weaker of my creations carry the scars of their progenitor's birth inside of them."

This indicates that Knull's more powerful, refined creations (i.e. the Grendel) were no longer vulnerable to fire and sonics.