I agree that the bottom sponge is a bit distracting. I love the image overall but wish it wasn't so hard to make out the details on the crab. Maybe a tighter crop would help?
What a thrill it must be to observe and photograph beneath the sea waters! What interesting and beautiful creatures and other structures exist there! The only thing about this that I would consider a distraction or fault is the middle bottom oof area; but to me, it is not a huge distraction.