What tool to use for invasive roots?

[tonsafun]

I have recently started trying to get my back lawn nice, after a couple of years of not doing anything to it. I have found that there is roots of some sort of creeping "bush?!" Dotted at the back. The main stalk is at most a thumb thick. My question is what would be the best hand tool to remove these? I was looking at the spiral hand cultivator.

 

[Anniekay]

If they're that big you probably need a shovel or a yard fork. I think you'll be working yourself to death with a hand tool.

 

[Oliver Buckle]

I would go round the edge with a spade, straight down a spit deep. When I came to something that it wouldn't go through I would use the club hammer on the foot ledge to cut through it.