I cought my riccordia eating my lettuce slug

I pulled the slug off, he is still alive, but really doesnt look good. I know they are hardy, but he had barely recovered my dropping a rock on him.
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55gl mixed reef pre-drilled
500w MH (120), 10 gl sump, cheap skimmer
tank est. spring '06
Is it wrong to love a clump? MACRO MANIA