lost 1 cluster of zoas to it. totally gone... initially suspect only, then when lights off saw a few moving around and zoas size reduced greatly in the morning with bite marks... :S then thought leave for 1 more day, and my zoas completely gone...... situation more stable (no more lost of zoas) after I clean them off which i discovered SO MANY of them hiding within a GSP rock.
then in another fowlr tank, these are nice to clear the food.. post no harm and not getting too big, so I leave them alone for my pistol shrimp to play with. (could hear some clicking sound at night.. )