Ok, I couldn’t find this anywhere, so I’m proud to be the first to give a Guide to the Clam Waters in Aqua Grabber update. The Giant Clam is where the treasure used to be. to the right of the clam is a “Pearl Shaped Rock”. You grab it and place it on the Clam’s mouth. Then, you grab the Grand Pearl.
The pearl shaped rock is what I’m holding in the image.