Ok that is what I thought it would be. That is a Diodogorgia or common name Red Finger Gorg. First, the good news they do wax over. Do give it a good week then gently rub it between your fingers and it "should" reopen. That or increase the flow around it and nature will take care of it. For feeding, those are meat eaters. They love cyclopeeze. Another great choice is Fauna Marine's sea fan food. Cyclops are fine but I would soak both of them in phyto for an hour before you feed.
Now the bad news, those wax over because your phosphates are too high. It is a stress reaction to protect itself from algae. Basically it she'd it's skin to get rid of algae that is growing in it. Best of luck, love those