Radiolarians

The silicate skeletons of single-cell plankton organisms such as radiolarians and diatoms have been used for well over a century as examples of complex microscopic forms in biology. (See page 385.) Most likely their overall shapes are determined before they harden through minimization of area by surface tension. Their pores and cross-linkages presumably reflect packings of many roughly spherical elements on the surface during formation (as seen in the mid-1990s in aluminophosphates).