The green-handle tool you see here is called a "barbed" broach.

And true to its name, its working end has a number of minute spikes sticking off its sides, not unlike a strand of barbed-wire.

A dentist will insert a broach into a tooth's root canal, so its barbs snag the canal's pulp tissue.

Then, when it's pulled out, much of this tissue will come with it (like you see in this picture).

So, what you are looking at here is literally the nerve pulled right out of a tooth.

By the way, since the patient was numbed up, they didn't feel a thing.