Calcium carbonate-based biominerals, also referred as biocalcifications, are the most abundant biogenic mineralized products at the surface of the Earth. In this paper, we summarize general concepts on biocalcifications and we sketch macro-evolutionary trends throughout the history of the Earth, from Archean to Phanerozoic times. Then, we expose five fundamental issues that represent key-challenges in biocalcification researches for the coming decade: the first one concerns the comprehension of the micro- and nano-structure of calcium carbonate biominerals from a mineral viewpoint, while the second one deals with the understanding of the dynamic process of their fabrication. The third one treats the subtle interplay between organics and the mineral phase. The fourth issue focuses on an environmental challenge related to ocean acidification (OA); at last, the diagenetic processes that affect biogenic calcium carbonate mineral constitute the fifth issue.