That "contraption" is an old pier from the 1800's that got destroyed and has been laying under water. There are actually two massive pieces that you can only see from out in the water. They used to send logs off to Chicago and the rest of the US to build homes out of the huge Michigan white pines back then.
(Shhhhhhh....I figured that out, but why ruin a chance to mess with ya?)
That water sure looks inviting. I love swimming in such clear water and snorkeling to check out all the under-water goodies to be found. Of course I might need a wet-suit to ward off the cold.;)
By the way...I haven’t gotten any pics of your flowers yet. ;) Isn’t this how this all started?