Like cells involved in mineralization in mammals, and surrounded by mineralized matrix (ameloblasts, odontoblasts, and osteoblasts), P. carterae is a polarized cell. In both cases, the mineral is a calcium crystal, the mineralization is biologically directed, and involves a highly charged calcium carrier.
There are differences, however. The calcium crystal in the algae, CaCO3 in the calcite form, is produced intracellularly, and in enamel, bone, and dentin, formation of hydroxyapatite crystals occurs extracellularly. The calcium carrier in the algae is a carbohydrate, and in mammalian dentin, it is a phosphoprotein. Also, CaCO3, in the form of shell implants, was used to replace teeth by the Mayans.