If you haven’t seen Black Panther yet, you’ve still probably heard about vibranium. But, um, what is vibranium exactly?

For starters, vibranium isn’t an element you’d remember from your high school chemistry days learning the periodic table, though it certainly sounds like it could be, amirite? The material is, in fact, a metal found in Wakanda, where Black Panther is set. Vibranium fuels Wakandan life, it’s entirely fictional, and it’s pretty damn important within the MCU…

Okay, so that covers what vibranium is, but why is it so important in Black Panther, specifically?

Warning: Some spoilers here…

Ulysses (Andy Serkis), an illegal arms dealer whom we first met in Avengers: Age of Ultron, had stolen a bunch of vibranium back when T’Chaka, T’Challa’s (Chadwick Boseman) father, ruled over Wakanda. After T’Chaka’s death, T’Challa/Black Panther becomes king, but things don’t exactly go swimmingly, because guess what? Ulysses is out for more vibranium, with Erik Killmonger (Michael B. Jordan) along for the villainous ride.

What exactly do they plan to do with the stolen vibranium? That’s definitely a question better left to the big screen. But thankfully, Black Panther is now in theaters.