Tiny sea creatures that he could not feel had attacked his flesh, leaving him standing in a pool of blood.
Jarrod Kanizay took to the waters off the Dendy Street beach with a pool net last night, hoping to figure out what underwater monstrosity nibbled on his son Sam's legs.
Despite their best efforts, doctors were stumped and Sam's legs continued to bleed, so he was transferred to Dandenong Hospital for further treatment and analysis.
Mr Kanizay said the injuries were a "freak incident" and has since received a biopsy and a number of stitches as medical experts try to piece together what happened.
"When he got out the ocean, he described having sand on his legs, so he went back in the water", his dad Jarrod Kanizay told AAP.
Jeff Weir, the executive director of the Dolphin Research Institute, told ABC he had suffered a similar experience.
He took a video of dozens of the tiny bug-like creatures chomping on the chunks of meat.
Sam Kanizay's feet are seen covered in what looked like hundreds of bleeding little pin holes.
After about half an hour of wading through the water, Kanizay walked out with what his family described as tiny creatures feeding off his legs, nearly like a scene straight out of a horror film.
Jarrod Kanizay said his son arrived home with what "looked like a war injury" and that his legs would not stop bleeding.
In a press statement Monday, local authorities reported that marine scientists had identified the flesh-eaters as lysianassid amphipods, a type of scavenging crustacean sometimes called "sea fleas". "They're mostly less than a centimeter long, and so the bites they make are pretty small, and so that's more consistent with pinprick size marks". "Some people thought that it was sea lice, but nobody really knew anything".
"You really need your feet for this game so we were advised not to go down there", he said.
"We're a really positive family and we expect a full recovery", he said.
While Sam was being treated at Dandenong Hospital, where doctors were mystified by his condition, his father was determined to get to the bottom of what had attacked his son.
He said: "It's not a parasite I've ever come across".
In a Facebook post, Richard Reina, an associate professor at Monash University's School of Biological Sciences in Australia, refers to "sea lice" as the cause of Sam's injuries.