Throughout nature, organisms have evolved to produce exquisite structures through a process called biomineralization.   This is especially true in the case of diatoms, which produce complex, hierarchical structures.   For example, the marine sponge Euplectella sp. comprises at least seven hierarchical levels within its silica skeleton.

Nanoparticles appear to be the basic building unit of many biomineralized structures.   Proteins in the organism direct the assembly of nanoparticles into these complex structures.