PODS:
Interesting, i didnt actually realise the size difference of pods and just how small copepods actually are...
Diet: Copepods eat bacteria, diatoms, and other tiny, single-celled organisms in the water. Maxillae, maxillipeds and antennae push food towards the mandibles (jaws), which process the food.
REF: http://seapods.com/
Interestingly a sponge is a breeding ground for pods. Keep one in the corner of your reef and they will breed in it. Rinse it out every couple of weeks to release the pods into the water. Might try keeping one in the fuge.
DIATOMS:
The skeleton of a diatom, or frustule, is made of very pure silica coated with a layer of organic material. This skeleton is divided into two parts, one of which (the epitheca) overlaps the other (the hypotheca) like the lid of a box or petri dish. Observe the diatom frustule below, in which the two halves have been pushed slightly askew
ref: http://oceanworld.tamu.edu/resources/oceanography-book/marinefoodwebs.htm