Talk about Bacillariophytes.

AKA Diatoms/ mostly unicellular with some colonies that are important phytaplankton/ plastids contain chlorophyll a and c and fucoxanthin (carotenoid brown) /siliceous walls called frustules formed of two halves, (epi and hypo) fitted together/ have different straition and markings that are species specific/ reserve substances are lipids and carbs water soluble/ chrysolaminarine (vacuoles stored)