Crystallization of calcium carbonate, typically, progresses sequentially via metastable phases. Amorphous CaCO3 (ACC) generally forms initially, both invitro and invivo, and is the precursor of the predominant anhydrous polymorphs (calcite, aragonite, and vaterite).[1–13] A new picture of the crystallization of calcium carbonate is emerging, which involves transformations of clusters to ACC and eventually to crystalline polymorphs.[14, 15] This stepwise manner has implications for the understanding of biomineralization [16] and of crystallization. ACCs that contain additives display order over atomic length scales that are related to crystalline polymorphs;[1–3] ACC synthesized at high supersaturation levels without additives,[17–20] on the other hand, show no distinct short-range order.[21, 22] Herein, we analyze proto-crystalline features of two amorphous intermediates, ACCI and ACCII,[15] and discuss their relevance for crystallization of CaCO3. We rationalize the identification of ACCI with pc-ACC (proto-calcite ACC) and ACCII with pv-ACC (proto-vaterite ACC), respectively. These ACCs were precipitated from metastable solutions of calcium carbonate at different pH values by destabilization in excess ethanol.