Any ideas?

In the last few months I've done a lot of walks with H and spotted quite a few of these type of things. Not a clue what they are but have seen them on the road and footpaths, especially near roadworks. Finally took a picture of one and the only thing anyone has suggested is car springs. Really? spring, It is rusty I guess.  Thought maybe they were some sort of clip for materials used in roadworks but that's just a wild guess...