fossilized

Short definition from Wiktionary

Adjective

1. 1
   In a state of fossilization; preserved in rock.
2. 2
   Old-fashioned, outmoded, or rigidly fixed in a way that is resistant to change.
3. 3
   Having become a fossil; no longer productive.

Verb

1. 1
   simple past and past participle of fossilize