Biosilica aging: From enzyme-driven gelation via syneresis to chemical/biochemical hardening

► Sponge skeleton/biosilica is synthesized by silicatein at physiological conditions. ► During aging of biosilica alkali metal ions are removed from biosilica. ► Silicatein-associated protein silintaphin-2 accepts the metal ions. ► Presence of silintaphin-2 intensifies silicatein-mediated biosilica formation. ► Reaction mechanism presented explains the structuring process of biosilica.