camouflage crab

i am new to saltwater and i have a question that is killing me. i had a camouflage crab for 2 months and just recenly bought a frag. of polyp. and my crag is taking them off the stem. what to do? are they going to dye in the crabs legs? i just saught one open in his leg. what to do? is it going to damage my frogspawn frag? please help thank you