Editing Seashell (section)

=== Plankton and protists ===
{{further|Protist shells}}
[[File:Diatoms through the microscope.jpg|thumb|Marine [[diatom]]s form hard silicate shells]]

Plant-like [[diatom]]s and animal-like [[radiolarian]]s are two forms of [[plankton]] which form hard [[silica]]te shells. [[Foraminifera]] and [[coccolithophore]]s create shells known as "[[test (biology)|tests]]" which are made of calcium carbonate. These shells and tests are usually microscopic in size, though in the case of foraminifera, they are sometimes visible to the naked eye, often resembling miniature mollusk shells.