Answer: diatoms

AnswerCrossword Clue
DIATOMSTypes of algae
DIATOMSPlankton particles
DIATOMSMicroscopic freshwater algae.
DIATOMSMicroscopic algae.
DIATOMSCertain algae
DIATOMSFreshwater algae
DIATOMSAlgae
diatomsDIATOM, any of a class of algae