Sounds like you have "q-tip" sponges in the filter. They attach in various places and filter-feed.
'pods look like little shrimp. Copepods, at least in my tank, are very small, like white moving dots on the glass and rocks. Amphipods look like small shrimp, about 1/8" or so for the big ones. Mine crawl around in the substrate and in the macroalgae in the refugium.
What I should do, though, is go home and check my invert zoo books for better definitions.