LPS coral...is this normal?

[Coasting]

Ive had a few appear on Euphyllia frags ive gotten in the past and it seemed to me that when the barnacle was out feeding it would irritate the coral so it wouldn't fully expand to my liking. Little bit of superglue in the barnacles hole fixed that problem. Otherwise no their not bad.

[Dearth]

Like all shellfish barnacles are filter feeders and are harmless per se if your worried about it cover the opening with a paste or glue and it will kill it