ACC particles would initially form due to an interaction of specialized matrix macromolecules bound to chitin in the CaCO3 precipitation process. Then, phosphoenolpyruvate (PEP) and 3-phosphoglycerate (3PI) would act by binding to the surface of ACC, thus inhibiting the transformation of ACC into a crystalline polymorph [25]. Citrate might be also involved in ACC stabilization by forming citrate-Ca2+-P complexes [24].