There has been a mystery concerning the formation of the shellfish carapace. It has been said that the animal "fixes" the calcium of the sea, but this is another unfounded assertion.
One day my grandchildren brought me a crab that was in the process of molting; it was a soft mass. So that it would continue to live, we placed it in a cave containing a very small amount of seawater. The next day it had already acquired a firmer carapace, which was completed the day after. In approximately thirty hours a crab forms its carapace, which, for a 17 X 10 cm size, weighs 350 grams. The calcium content of seawater is very small (on the average, Ca = 0.042%). The molting shellfish is unprotected from marine animals and, being very vulnerable, it hides and does not hunt.
A body analysis of the crab has shown that its hepato-pancreas alone stocks a small amount of limestone (calcium carbonate) before the molting, but that its carapace contains forty times more limestone than its pancreas. Then?
We have seen that the magnesium (and potassium) found in seawater (5% magnesium salts and 0.5% potassium salts) can give calcium and that it is essentially magnesium, which is utilized by the shellfish to make its carapace.
At the Maritime Laboratory of Roscoff, a crayfish was put in a seawater basin from which limestone had been removed by precipitation; the animal made its shell anyway.
Chemical analysis made on animals secreting their shells has revealed that limestone is formed on the outer side of a membrane although on the opposite side of the membrane, where matter enters, there is no limestone. This fact has left specialists perplexed.
Of course, scientists who have been experimenting in this field are criticized by other analysts; that is in the order of things. But the innovator is not always wrong; nothing is perfect (the perfect being inaccessible to man) and someone will always find a point to criticize, for that is how progress is made. I will therefore refrain from claiming that the methods I have used thus far are perfect. However, I judge results valuable when they are of relative value when measured against variations obtained by the same method.
I have accepted the research of the authors cited, insofar as they provide strong guarantees. With this research the chemists-biologists demonstrate, themselves, that with regard to living matter there are inadequacies in Lavoisier's law concerning the conservation of matter. Thesis judges concur with them, thus showing that our conclusions concerning the failure of Lavoisier's law in the field of biology are beginning to be officially admitted.
taken from: C. L. Kervran: Biological Transmutations, ch. 8