fossilised

(verb) convert to a fossil. Synonyms: fossilize, fossilise. Example: "The little animals fossilized and are now embedded in the limestone."

(verb) become mentally inflexible. Synonyms: fossilize, fossilise.

(adj) set in a rigidly conventional pattern of behavior, habits, or beliefs. Synonyms: fossilized, ossified. Examples: "Obsolete fossilized ways." "An ossified bureaucratic system."