The “Prince Rupert’s Drop” may sound like a silly moniker for a piece of glass, but don’t let the name fool you: These strange baubles are almost indestructible.

Created by plunging molten glass into freezing water, the bulbous ends of these unusual tear-dropped shapes are supposedly nearly impossible to break.

That’s not an unfair assessment: PRDs have been shown to withstand not just blows from a hammer or an impact on a concrete sidewalk, but a straight shot from a .38 Special loaded with some custom-made full metal jackets, thanks to the inquisitive Destin Sandlin at Smarter Every Day.

prince-ruperts-drop-shotsGIF via SmarterEveryDay

Unfortunately, the Prince Rupert’s Drop isn’t totally indestructible. As part of his quest to test the true strength of the PRD, Sandlin opted for a something a bit more intimidating for his test this past Sunday: the legendary AK-47.

Here’s the interesting thing about this video: While the first AK round completely disintegrates against the PRD, the second shot completely shatters the solid glass teardrop into dust.

landscape-1493669937-prdGIF via SmarterEveryDay

The moral of the story: Everything is “indestructible” until it meets an AK-47.