sentence: Most diatoms are unicellular, although some form chains or simple colonies.
sentences_before: They are one of the most common types of phytoplankton.
sentences_after: These walls, called frustules, take many forms, some quite beautiful and ornate. They usually consist of two asymmetrical sides with a split between them, which gives the group its name.
concept_name: diatom
headings: Diatom
categories: Protista Algae