I think that like others have pointed out this was a man made habitat and that the effigie was placed in the tank for what ever reason.
I am sure you dive, right or know divers. When your under you always keep an eye out, I started my diving years in the Army, and even then beit training or real world there was always a purpose, and many of times under I had things catch my eye that was not part of the task at hand. I would wager to say that nearly every diver has a higher natural level of curiosity than most people.
This past mothers day my wife went under to MD at a lake in Germany, a place that was nailed with flooding not too long ago. This lake used to have tons of Jon boats just left on teh shore by the fisherman who use them. Flood warnings came after the Rhein breached the banks (sounds about normal), major RV site lost everything, boats just gone and not found, RVs washing away, cars it was just wild.
So my wife comes up to unload her finds bag and go back down; she says hey I found a bunch of Jon boats and row boats down there. She said do you think those people where not smart enough to even look and assumed it washed away. We reported it to a mate of mine who Commands the local THW (Emergency Disaster Agency in Germany) in that area, he said they had always suspected it but with no proof there is no exploration funding for private property. He said it was only a matter of time before some went down and found boats or other property so funding could then be cut to recover, in turn justify their job and make the local government look good like it is a clean up act and getting people their stuff back.
Point is, no matter why you go down you normally see or find something else that catches your eye; 100% plant. Had that not of been a plant then it would have been cut in editing because they would figure viewers would not watch a scientific doc if the beaker can not even spot a gold bar. No octa is that captivating, not even to the biggest nerd. The biggest nerd would have found that and thought of more funding for exploration on a government grant. LOL
Just my thoughts though, but still a scream at the TV scene totally.
So what are you saying ?> ?
That you think its staged / set up ? ? ?