The ABSa15 cell line is derived from the calcified branchial arches of a gilthead seabream and is capable of extracellular matrix mineralization. Gene expression analysis is suggestive of pre-chondrocyte lineage. Extracellular matrix mineralization occurs on supplementation with calcium chloride, β-glycerophosphate and ascorbic acid. Mineral deposits can be detected as early as two weeks of treatment and increase for up to four weeks. ABSa15 is useful for investigating the mechanism of cell differentiation, extracellular matrix mineralization and also the screening of mineralogenic molecules.