Any ideas what this is?

I found this in the garden of the house we recently purchased. Has anyone got any ideas what it is? It is obviously made of iron as most of it has gone rusty. There is a stainless steel loop around the 'middle'. At the top it has nylon cord wrapped around it - no idea it this would be original or added to replace something. At the bottom it has a cross with a flat spike on each end and a round spike in the centre of the cross. It is quite heavy and about 20 inches from top to bottom. I'm just curious to know what it is! Thanks