It's a big yellow U-lock structure; surveyed approx March.

Visible via non free images as well:
https://www.google.com/maps/@-34.8864402,138.5939662,3a,37.9y,290.13h,78.65t/data=!3m6!1e1!3m4!1sIjzJbN3OxP3-LZtn35NyLA!2e0!7i16384!8i8192