But one thing they won't notice is what he's missing.
"So I was born without a leg," said Marmino. "I had amniotic band syndrome, so without one since birth, so I didn't have to change anything, it wasn't through trauma. I was just born that way."
The seventh grader from Medford, who plays on both his middle school and club teams, has been through eight surgeries in total.
He has more surgeries coming to accommodate bone growth in his leg.
"We didn't know that he was going to be born without a leg, that was a big shock at birth. So to see him now, and then what I was like back in the hospital when he was born thinking, 'How is he going to do this? How is he gonna play that?' And to see him, look who's laughing now. He's just doing it all," said Marmino's mother.
"A lot of people get confused. They say, 'What is it like to have one leg?' But I don't know what it's like to have two legs, so I can't really answer that question, you know?" said Marmino.
Baseball is Marmino's first love, but if you think it's the only sport he plays, you would be wrong. In fact, some say he's got too many talents!
"I used to do Jr. Paralympic track, I play sled hockey right now, I play baseball, I surf, I like to snowboard, I skateboard, I've played basketball, I run a lot," said Marmino.
And if that wasn't enough, next he's adding "Hollywood actor" to the list.
Back in 2021, Marmino was "discovered" on his Instagram page and invited to audition for an Apple TV+ show about a young amputee called 'Best Foot Forward'.
He won the role and spent four months in Los Angeles shooting the series!
"It was definitely a shocker, I didn't think I was going to be very good at it but apparently I was, you just kind of got to act natural," he said.
"The first time seeing his face on the streaming page, there were tears. But it was nuts, it kind of goes back to what I said before, he will try anything, do anything, and he succeeds at it," said Marmino's mother.
An actor, an amputee advocate, and an athlete, there's nothing Marmino cannot do. And with that in mind, he tries to inspire others to follow suit.
"I always say #NoLimits, like not letting anything stop you from what you want to do, not letting anyone tell you what you can and can't do. Yeah, that's really my message," he said.