Cal-Assimilate Plus by Klaire Labs is a calcium magnesium supplement containing calcium in three forms: hydroxyapatite, microcrystallineand and a natural bone mineral. Calcium is essential for all living organisms, especially in cell physiology where Ca2+ ion is moved into and out of the cytoplasm and functions as a signal for many cellular processes. Calcium is one of the most abundant elements by mass in many animals and has an important role in the mineralization of shells and bones. Cal-Assimilate Plus by Klaire Labs contains two forms of magnesium along with many other key materials and vitamin D which are helpful in assisting in optimal calcium absorption and metabolism.