The Grossest Thing About Iron Man's Armor Still Makes No Sense

Tony Stark's Iron Man armor and the arc reactor that powers it have worked wonders for Robert Downey Jr.'s MCU hero. But despite all the protection his suit offers, there's still a pretty glaring flaw in Tony's defense that the movies never really touch on: Isn't there a giant, gaping hole in the middle of Tony Stark's chest? Like, right where his heart should be?

The first "Iron Man" movie establishes how Tony invented the miniaturized reactor technology to both prevent shrapnel from entering his heart and to power his primitive Mark-I armor, but it's never explained exactly how Stark and Yinsen (Shaun Taub) were able to do invasive open heart surgery in a cave, much less how Stark can walk around with a good chunk of his sternum seemingly removed. By the end of "Iron Man 3," Tony no longer needs the reactor, having had any leftover shrapnel extracted, but we still never see how he was subsequently sealed back up.

The first movie sees Tony with a hole in his chest big enough for Pepper Potts (Gwyneth Paltrow) to fit her entire hand in, but that is apparently a trivial enough issue that it didn't warrant much screentime to explain away. "Avengers: Infinity War" sees Tony once again sporting chest-mounted Iron Man tech, but instead of powering his suit, this new unit completely houses it via nanotechnology. While that helps him to face off against Thanos (Josh Brolin), it still doesn't explain how he has been surviving with essentially an empty Pringles can where his vital organs are supposed to be.

While Tony Stark/Iron Man has been around since 1963's "Tales of Suspense" #39, the idea of his life-saving power source being embedded in his chest is a fairly recent one. In his comic book debut, much like in the movies, Stark's suit prevents shrapnel from piercing his heart, but it's not integrated into his body. The core piece of his original suit is a simple electromagnetic chest plate that he must always wear, but it's totally external.

Of course, like his MCU counterpart, Tony's comic book tech has seen countless upgrades and reimaginings over the years. But the chest cavity we see in the early MCU movies was never originally part of his character. In fact, his original suits were so relatively low-tech that he'd have to plug them into the wall like he was charging his phone. 

Pepper famously gave Tony a keepsake — his rudimentary original arc reactor — in the first "Iron Man" movie. It served as proof that "Even Tony Stark has a heart." And while that may be true, the movies make it hard to tell where exactly it can exist within his body after his accident.