Mollusc shell formation requires calcium (Ca ) and bicarbonate (CO₃ ⁻) ions, transported through the mantle via the hemolymph, and the secretion of an organic matrix that interacts with the mineral ions to form either the aragonite or calcite polymorph of calcium carbonate (CaCO₃). The biomineralization process takes place in the extrapallial space, between inner shell and outer mantle epithelium, and is believed to be under the control of calcium-binding proteins and hormonal factors such as calcitonin-related molecules (CGRP-like peptides). Epithelial cells from the mantle are responsible from the secretion of matrix molecules whereas hemocytes are involved in ion transportation during shell formation and regeneration. To understand the biochemical and cellular events implied in the biomineralization process, we developed primary cell cultures from the nacreous gastropod Haliotis tuberculata. Mantle cells as well as hemocyte cell cultures were successfully maintained in vitro and evaluated for their viability and proliferation using semiautomated assays. The effect of calcitonin-related molecules (h-CGRP) on cellular activity and proliferation was evaluated in those primary cell cultures. The results indicate that human-CGRP modulates the activity of both mantle cells and hemocytes and increases carbonic anhydrase activity in vitro. These results are consistent with those obtained in vivo, supporting the hypothesis that CGRP-like molecules control the activity of target cells involved in the biomineralization process.