The test revealed that rooks can use two tools in succession to get the worm
Four rooks have stunned scientists by making tools to get food, something they've never been seen doing before.
The birds were smart enough to drop stones onto trap doors to release tasty treats, and even bent wire into hooks to grab a basket of food.
The clever birds were being tested by researchers in a laboratory in the University of London.
Some other birds use tools in the wild, but not rooks, which makes this discovery very interesting.
The rooks were able to fashion wire into a hook to fish out the bucket of food
The four rooks, called Cook, Fry, Connelly and Monroe, also showed they could use two tools, one after the other, to complete a task.
Only one other species of bird, the New Caledonian crow can do this.
Christopher Bird, from Cambridge University, was impressed with the rooks.
"We have found that they can select the appropriate tools out of a choice of tools and they show flexibility in the types of tools they use," he said.