Looks like some of the smaller pods on the glass are munnid isopods. Great critters and good food for mandarins. They are herbivores and ulva is one of the best foods for them, good for amphipods to. So you'll need to buy more ulva from time to time. It takes awhile but they will eventually eat it all.
What about this isopod? Maybe too big?
~ Z 's Pods, Harlequin Shrimp Pair, and Beemer, King of the Nano ~
~ Collector of the rare and unusual (or just plain expensive) ~