Took me a while, but now I see it. I believe what you are looking at is a depression in the coral that happens to have the odd aircraft shaped look to it. It can look like the inverse, where it seems to be an object, but is actually a void. If you notice, there are a bunch of shadows visible - the dark spots all on the south east side of several corners which happen to be in line with the shadows from the trees. In the end, I don't think that what you see, or think you see, is there. It is coral formations and the gaps between them.
Andrew