Cut marks on the eyeball suggest it was cut out of the fish's head at sea by a fisherman who then tossed it overboard, NBC News reported Monday.
There had been speculation the eye might have come from a giant squid or even a whale, but officials at the Florida Fish and Wildlife Conservation Commission said a swordfish -- which can grow to 1,000 pounds -- was the likely source.
"Experts on site and remotely have viewed and analyzed the eye, and based on its color, size and structure, along with the presence of bone around it, we believe the eye came from a swordfish," Joan Herrera, curator of collections at the FWC's Fish and Wildlife Research Institute in St. Petersburg, said in a commission release.
"Based on straight-line cuts visible around the eye, we believe it was removed by a fisherman and discarded."
Pictures of the giant eyeball flooded the Web following its discovery on Florida's Pompano Beach Thursday.
"It's definitely been unusual to have a situation quite like this," said Kevin Baxter, a spokesman for the Florida Fish and Wildlife Conservation Commission.