Here you go Ritchie
She found this to start with which I missed. She didn't put any pointers as to what we are looking at so I've added them.
Red: the thickness of the material
Yellow: the remainig straight edges
Blue: the square holes

Now, I have re-run the video from before and after the time displayed in the picture and, the ROV appears to parked on the reef for quite a while so, no camera blur or distortion.
I am pretty open to ideas on this but, coral creating SQUARE holes mmmm and, why is it so thin with shiny edges in the ROV lights.
All I am saying is, this is the one of the better examples of thin metal sheeting scattered about here.
I didn't give her any clue as to what we were hoping to find here buy, that's the first thing she found. it will be a week or two before I get anything more some magazine assignment or something.