This is not what you may think at first sight. These are book-ends, made of concrete by a person I know (we happen to be colleagues). Put one of these in your bookshelf and the bookshelf will stay organized and you won’t hear that bum-ping noice from falling books again.
I thought they were unusual and a bit fun too, so I asked if could take a couple of photos of them and she didn’t object to it so here they are. I’ve said it before and I say it again “Concrete can be beautiful sometimes”.