McDonald's Chicken McNuggets are one of the fast food juggernaut's core menu items. They're offered all over the world and are gobbled up by the millions.

McDonald's has to make sure every piece is as perfect and standardized as possible — all the way down to the shape of the chicken.

So, there's a method to the McNugget madness.

We visited the McDonald's headquarters in Oak Brook, Ill., and sat in on a quality testing session. They had flown in chicken pros from suppliers like Tyson to grade the nuggets.

The McDonald's sensory team explained that Chicken McNuggets have four distinct shapes and in order to have a chance to meet the McDonald's "Gold Standard" for quality, they have to match them as perfectly as possible.

And each of those shapes has its own name.

Here are the four shapes of Chicken McNuggets, according to Barbara J. Booth, director of sensory science at McDonald's USA:

Ball

Bone

Bell

Boot

Elsewhere, it seems that McDonald's uses a different name for the "bone."

"There are four different Chicken McNugget shapes (the "boot," "ball," "bow-tie" and "bell")," McDonald's Canada wrote on its Q&A page.

But the perfect McNugget needs a lot more than a well-aligned shape, according to McDonald's standards. The company tests flavor, breading texture, meat texture, bite firmness, color, coating, and a whole lot more. It's a strangely thorough process.

Of course, if you've ever eaten at McDonald's, you know that this doesn't mean the nuggets come out perfectly every time in restaurants.

It's bad when you get a tiny, mutant McNugget in your box, but it's even worse when you get a whole batch of cold, soft ones that weren't prepared properly by staff.

Disclosure: McDonald's provided travel and accommodations for the trip.

