Food for a Sailfin tang

[Azilla]

Ok well here is a strange one. I have been puttin strips of nori in my tank and when i walk away and come back it is gone. I know the shrimp tears it off then it floats around but it always goes missing. Well tonight i watched. I put the strip in the shrimp came over tore it up then ripped off the entire chunk it floated around the tank then i saw my bubble corals tenticles come out and it grabbed the nori sheet. As i watched the bubble coral ate the entire sheet of nori right before my eyes................ Now i didnt know they ate this kinda stuff???