The valves often bear radially symmetrical ornamental patterns that can appear as dots when viewed with an optical microscope.

Some also bear spines on their valves, which may either increase cell surface area and reduce sinking, or act as a deterrent to zooplankton grazers.

In sexual species, oogamous meiosis produces haploid gametes, either ova or sperm cells.

[5] However, diatom taxonomy is changing due to the development of new molecular and genetical analysis tools.

[4] Tremarin, Priscila; Veiga Ludwig, Thelma Alvim; Torgan, Lezilda Carvalho (November 7, 2014).