Albertan are you sure it isn't a pistol shrimp? Have you actually seen the little guy before? I keep my duncans right off of the sand on a piece of live rock and they tend to do really well (I target feed allot) but I know that Ric's have a really nasty sting so that and the epoxy has probably ****ed them off. Although you can epoxy them I find that because duncans have tissue coming up the stalk (As shown below):
That using super glue on the base of the skeleton works the best, this way you don't have any necrosis that takes off due to smothered tissue. Hope he pulls through, keep the target feeding up.
Levi