Unlike other sharks, their teeth are small and blunt, to grind the shells of molluscs they can feed on after sucking in water and sand from the ocean floor and blowing the waste out their gills.
Hatheier's mother was swimming with the local club "The Jellybean Minstrels" when she spotted the shark.
While Hatheier was applauded for her bravery, she said she knew Port Jackson sharks are relatively harmless. Still, rescuing it isn't something most people would attempt.
Not keen on finishing her swim early, a Sydney women made a decision to throw the pesky shark out of the pool.
"He was pretty distressed and bumping into things, so I just followed him around for a bit. I was feeling sorry for him", she said.
"I thought, as long as I keep my hand near its fins it couldn't bite me; I wouldn't have grabbed it by the tail though".
Desperately wanting a safe swim, Melissa Hatheier was filmed wrestling with the unexpected guest at the Cronulla Beach rock pool. So I said, 'I think I can just grab him.' So I herded him into the shallows and then I just sort of got on my knees. Then I left him to side of sheep, "he used his statements".
"I'm a real estate agent".
"I picked him up and thought 'he's not even that heavy". She described holding the shark in her arms as "kind of like a toddler", according to the BBC. "It was pretty amusing". "That shark owes its life to you". She was cheered online, too.
"Not all heroes wear capes", another wrote.