Looks like a device to be towed behind a tractor. The chains and spikes probably rake the ground. Collapsible design for delivery on a trailer. I'm no farmer/game keeper but is it something to do with grouse moors?
Modern art?
It's definitely a harrow, possibly placed there ready to make firebreaks for when they're burning the heather....from a distance it does look like it's fallen off an aeroplane though.