Sounds like infectious would fit.
For the leaves to be presearved as fossil, they have to undergo a natural process of carbonization. This involves a slow chemical reaction with water over time that allows oxygen, nitrogen, and hydrogen to escape the leaves’ structure as gases leaving behind a carbon skeleton/film.
Homeostasis is maintained by negative feedback loops within the organism. In contrast, positive feedback loops push the organism further out of homeostasis, but may be necessary for life to occur. Homeostasis is controlled by the nervous and endocrine systems in mammals.