"23. Amphipods, which I have only witnessed eating sick, dead, dying, decaying polyps. Doesn’t mean they won’t eat perfectly healthy ones, I just haven’t witnessed it, some have."
The pods that did this to me looked much different than other pods in the tank.
Also, I saw/experienced some red/brown looking things not on your list, maybe some other type of crustacean that "jumped" off in a freshwater dip.