It does look like it could be the hydno, however I'm not all in on that until I see a picture under just day light, or a better picture in general.
An even better picture will be out of the water and the flesh fully retracted to see skeletal shape, becasue it doesn't seem to have the chanels that the hydno does, seems to have each round polyp, but until a better picture I cant tell for sure
Since there is so much interested in this thread, I will take a pic of the specimen after taking out of the water and in sunlight. Hope it should help then.