In their quest to protect the American skies, TSA agents, like law enforcement officials the world over, end up dealing with some weird stuff - like when someone tried to check a human skull through security.

As part of its review of 2013, the TSA posted on its blog some of the most unusual items it had the pleasure of confiscating from travelers this year. Here are some of the oddest:

Human Skull Fragments

The TSA said that in April, its officers in Fort Lauderdale, Fla. were having a relatively normal day until one passenger tried to check a bag filled with old pots. The pots themselves were not terribly out of the ordinary, but the skull fragments discovered inside one of them certainly was.

"While the fragments weren't a security threat, they did slow screening down a bit since the area quickly became a crime scene!" the TSA wrote on its blog.

A Mace, Old-Timey Edition

There's the self-defense mace spray, and there's the kind of mace that knights used to bash each other in the head in Medieval times. This is the second kind.

A few hundred years after they were popular, a TSA agent pulled one off an airline customer at Chicago Midway Airport in September.

A (Fake) Suicide Vest

If x-ray scanner didn't detect this thing, the TSA would have some serious problems. In Indianapolis International Airport in March, the x-ray machine's alarm went off and security officers were surprised to find what looked like a suicide vest, complete with electric matches and bags of what appeared to be explosives.

No worries, though, as all the items were "inert" and the vest just belonged to an explosives instructor.

"As I've said before, we're all too familiar with instructors and other people in this type of business needing these sorts of items for their jobs," Bob Burns of the TSA Blog Team wrote. "As with all inert training items and replicas, we don't know they're not real until we've checked them out."

Ninja Stars, a Lot of Them

There is a picture on the TSA blog of dozens of ninja stars and throwing knives and, according to the photo's caption, those are just "some" of those confiscated from travelers in 2013.

"Either leave these at home or pack them in your checked baggage, but be sure to check state laws before packing them, Grasshopper," the TSA wrote in another post.

WWII-Era Bazooka Round

Packed on top of some clothes and toiletries in a bag in Chicago O'Hare airport in January was a WII-era bazooka round. Luckily the round was inert, but it still attracted the TSA blog's somewhat sarcastic wrath:

"We continue to find inert hand grenades and other weaponry on a weekly basis," the TSA blog said at the time. "I know they are cool novelty items, but it is best not to take them on a plane."

Pen Knife

This tricky traveler had a knife hidden in what appeared to be a normal pen. No obvious jokes here about anything being mightier than the sword.