I have read they can pick at acans and do some damage but won't eat them. They need to be fed constantly so as not to do damage to acros and digitatas...here is some info gathered from another website
Eunicea mammosa, Swollen-Knob Candelabrum - mostly left alone
Euphyllia paranchora, Branching Hammer Coral - mostly left alone
Actinodiscus sp, Mushroom Coral - never bothered
Ricordea florida, Ricordia Mushroom Coral - never bothered
Zoanthus sp, Zoanthid Polyp Coral - never bothered
Sinularia spp, Tree/Finger Leather Coral - sometimes messed with causing coral retraction
Blastomussa wellsi, Blastomussa Coral - never bothered
Caulastrea curvata, Trumpet Coral - mostly left alone
Favites spp, Favites Brain Coral - mostly left alone
Blastomussa merletti, Aussie Blastomussa Coral - often messed with but survives fine
Goniastrea palauensis, Goniastrea Brain Coral - mostly left alone
Acanthastrea lordhowensis, Acan Lord Coral - often messed with, a few have perished
Echinophyllia aspera, Aussie Chalice Coral - never messed with
Montipora undata, Encrusting Montipora Coral - mostly left alone
Protopalythoa sp, Paly Button Polyp Coral - never messed with
Entacmaea quadricolor, Rose Bubble Tip Anemone - never messed with
Tridacna crocea, Crocea Giant Clam - never messed with
Dendrophyllia fistula, Dendro Sun Coral - mostly left alone
Platygyra sp, Brain/Worm Coral - mostly left alone
Xenia sp, Pulsing Xenia - never messed with
Pseudoplexaura sp, Sea Whip/Rod - often messed with but survives ok.
Pseudoplexaura sp, Sea Whip/Rod (yellow polyp) - never messed with
Acropora sp, Acros of all varieties - messed with to death
Montipora sp, branching Monti's - messed with to death
Montipora capricornis, Caps - messed with to death
Duncanopsammia axifuga, Duncans - often messed with but survives ok