Well, if I had to guess, I'd say it is probably a log that washed into that position. Black is the root ball, light is the trunk covered by a thin layer of sediment. Top has been broken off in the wind storm that uprooted the tree. Floated there and got caught up on the shoreline.
Based upon the anecdote of airplane parts being spotted out on the far lagoon shoreline (I can't recall the specifics at the moment), we did survey this area extensively in 2001 using metal detectors. We also surveyed this area underwater by skiff towed scuba guinea pigs (Walt and myself) in 2001, and I believe using the small AUV sidescan unit in 2010? Taraia point is one place where the sediment does accumulate, that is why it is there, and it does change shape a bit over time as it builds and erodes. Just off the tip, on the side where the log is, it is very loose fine grained stuff and easy to sink into, and very stinky, i.e. much like quicksand made from bird guano. As you move farther up the shore, it firms up.
My opinion, anything other than a log is an extreme long shot, but.....
Fun to speculate though.
Andrew