Emerald crab eating corals

All of a sudden my emerald crab is showing way too much interest in my corals. Not sure if he is eating them or picking stuff off them. This morning he had a death grip on my golden yellow polyp.....I recently introduced new corals and that seemed to be triggering the issue. Previously he ignored the corals.....Do I need to get rid of him or is he just cleaning them. I am new to the coral thing. 30L tank