silicon dioxide walls diatoms used in environmental assessment and monitoring diatoms used in environmental assessment and monitoring Diatom What's a diatom? westerndiatoms.colorado.edu 20,000 to 2 million species diatoms diatom What's a diatom? diatoms diatoms diatoms ossigeno diatoms diatoms westerndiatoms.colorado.edu Diatom ossigeno diatoms westerndiatoms.colorado.edu diatom diatom