#his lungs aren’t a giant muscle and instead like a balloon as most kids think they are

[thatrandomsarahchick]

Consider also: he eventually starts learning more about the human body as he ages, either through school or the local library, so his body changes every single time someone scans him.

He learns that there are both red and white bloods? Suddenly he had two sheerness coloured liquids running trig his veins. Later, he learns that they're actually red and white cells, swimming in a watery liquid. His blood changes to both have perfectly round white and red blood floating in salty water.

Billy learns that the uterus exists, so there's a very confusing 3 weeks where there's one of those floating around his gut.

He learns that the food tube and the breathing tube are different things, and suddenly, there's a second one going in a straight line from his mouth to wherever his stomach is at that moment.

He has a constantly changing amount of bones in his body.

Of course, whenever he's fully distracted and not focusing on his body, everything just dissipates. He's just a solid slab of muscle meat the entire way through.

What if when Billy gets put behind the x-ray and Batman's like "where are your bones" Billy panics, so bones appear, except, Billy doesnt actually? Know? How human bones work? So like, he just has a lot of bones under the x-ray now, except there are way too many and also that's not how ones are supposed to look like and fit in the human body??? Why is his whole torso from neck to butt covered in spines??? They're only supposed to be at the chest!

Marvel’s biology is strange. Batman knows that. After all, he and Martian Manhunter oversee the medical examinations of heroes. For some reason though, J’onn isn’t too concerned about it even though he definitely should be. That might be because of the fact J’onn’s a shapeshifter but still. Like…

Batman: “Say ah, Captain.”

Marvel: “Aaaaaaaah…”

Batman: *puts a popsicle stick on his tongue and looks around his mouth*

Marvel: “I’ evrythg gud? (Is everything good?)”

Batman: “Captain… Why do your teeth extend past your throat?”

Marvel: “Wha?”

Batman: “Why do your teeth continue past the normal amount until they disappear down your throat?” *gets a little flash light and peers it into Billy’s throat*

Marvel: “I’ tha no norma? (Is that not normal?)”

Batman: “No? Maybe?” *takes the popsicle stick away and turns off the flashlight*

Marvel: “How many teeth do normal people have?”

Batman: “32.”

Marvel: “Oh, okay. Check again.” *opens his mouth and he now has 32 normal teeth before closing it back up* “Is that better?”

Batman: “It is for humans.”

Marvel: “Oh, well then that’s good because I’m an adult human male aren’t I?”

Batman: Why are you asking me?

The fact that Marvel had to ask if he was an adult human male was extremely offputting.

or

Supes: *using X-ray vision on Billy* “Cap, why do you only have lungs, a heart and a brain?”

Marvel: “What do you mean?”

Supes: “I mean, you only have lungs, a heart, and a brain. How are you standing?”

Marvel: “Uh…”

Supes: “Is that normal for your species or something?”

Marvel: What do you mean species? I’m human?”

Supes: “Then how…?”

Marvel: “Can you show me a photo of human bodily innards?”

Supes: *confused at the suddenness of the question* “Why?”

Marvel: “Just cause.”

Supes: “Okay…” *shows him*

Random Bystander: *sees this and immediately thinks the two are gore fanatics*

Marvel: “Thanks! Now check again.”

Supes: “Woah… how do you do that?”

Marvel: “Well, I’m a human adult male. Aren’t I supposed to have those organs?”

Later, when Marvel told Flash about that incident…

Flash: “Geez, Cap. It’s like you were built by a kid!”

Marvel: “Ha ha ha… I know, right?”

JL: *laughing*

Marvel: *awkward laughing*

Batman: *sees the awkward laughing*

Bruce somehow came up with the theory that Marvel was built by a child God and that’s why his biology was weird despite the fact he claimed to be a human adult male. But then again, if he was built by a child God, would they want him to tweak his creation every single time he wishes to be more human?