Biological Transmutations and Their Applications in Chemistry, Physics, Biology, Ecology, Medicine, Nutrition, Agriculture, Geology by Professor Louis C Kervran (English translation by Michel Abehsera) is an investigation into the possible natural changing of elements into different forms by life forms such as animals and plants.
The original French version of the Biological Transmutations book by Corentin Louis Kervran was published a long time ago in 1962. Kervran wrote a number of follow up books. Michel Abehsera combined C L Kervran’s books into an English version that was published in 1972.
You can read an article on the Biological Transmutations book and calcium.