Answer: petrifying

AnswerCrossword Clue
petrifyingPETRIFY, to convert into a stony substance
petrifying(of organic matter) Become converted into stone or a stony substance in such a way
petrifyingChange (organic matter) into a stony concretion by encrusting or replacing its original substance with a calcareous, siliceous, or other mineral deposit
petrifyingDeprive or become deprived of vitality or the capacity for change
petrifyingMake (someone) so frightened that they are unable to move or think