Short answers, pulled from the story.
Biomineralization is the process by which living organisms produce minerals, often resulting in hardened or stiffened tissues. Organisms use organic macromolecules such as proteins and polysaccharides to collect raw materials and direct the nucleation, growth, and morphology of mineral crystals at ambient temperatures and in aqueous environments.
Over 60 different minerals have been identified in organisms. These span all six taxonomic kingdoms and include silicates, carbonates, phosphates, iron minerals, and more exotic compounds such as strontium sulfate.
Silica (SiO2 with variable water content) is the most taxonomically widespread biomineral, present in all eukaryotic supergroups. Diatoms are the most important marine silicifiers, with nearly all species requiring silicon to complete cell division.
Organisms have been producing mineralized skeletons for roughly 550 million years. Most animal lineages first expressed biomineralized components in the Cambrian period, though the most ancient example of biomineralization, magnetite deposition in bacteria, dates back 2 billion years.
Mollusc shells have a fracture toughness approximately 3,000 times greater than that of the calcium carbonate crystals they contain. Specialized proteins direct crystal nucleation, phase, morphology, and growth dynamics, and organic components including proteins, sugars, and lipids are woven into the shell's composite structure.
Microbial cells carry negatively charged surface ligands that attract the positively charged uranyl ion. When phosphate concentrations are sufficient, minerals such as autunite precipitate and reduce uranium mobility in groundwater. Stimulating bacterial phosphatase activity releases phosphate at a controlled rate, making the process more targeted than adding inorganic phosphate directly.
Biominerals carry organic biosignatures that persist long after an organism dies, making them durable indicators of past biological activity. On the 24th of January 2014, NASA reported that the Curiosity and Opportunity rovers would search Mars for evidence of ancient life partly by looking for such biomineral-associated signatures in environments that may once have been habitable.