natural action,
natural process,
activity,
action a process existing in or produced by nature (rather than by the intent of human beings); "the action of natural forces"; "volcanic activity"
plastination a process involving fixation and dehydration and forced impregnation and hardening of biological tissues; water and lipids are replaced by curable polymers (silicone or epoxy or polyester) that are subsequently hardened; "the plastination of specimens is valuable for research and teaching"
