On a recent vacation in Aruba I went snorkeling and saw a small reef octopus. I followed it at a respectful distance and it hid in what I'm guessing was its den, behind a pinkish rock. In this picture you can see one of its eyes peeking out and part of its body behind the rock. The octopus actually moved the pink rock out of the way once it realized I was floating above and wouldn't get any closer. I have photos of it looking at me after the rock was moved to the side. I was able to capture this image with my GoPro8.