fossilize

verb

1. (transitive)To make into a fossil.

   “Most of the booths had been scooped clean by the scalpel-sharp corner of the glacier in the crash. Three remained. Two of them were punctured and, inside, the once-human occupants had been fossilized into the walls by centuries upon centuries of patient ice.”

2. (intransitive)To become a fossil.
3. (broadly, figuratively, intransitive)To become inflexible or outmoded.

   “I was getting fossilised myself, but of late my stock of ideas has been very much enlarged.”

4. (broadly, figuratively, transitive)To make antiquated, rigid, or fixed; to deaden.

   “Ten layers of birthdays on a woman's head / Are apt to fossilize her girlish mirth.”

   “I'll meet you again Blanketed in soil Fossilized in photographs”