Answer:
A diatom has a cell wall made of silica.
Explanation:
Diatoms are eukaryotic phytoplankton cells known for their silica-containing cell walls (frustales), and are responsible for approximately 20% of total primary productivity globally. Diatom silica is a form of biogenic opal, containing oxygen isotopes and can be used in lacustrine and marine paleoenvironmental studies.
