The underwater mass of dead sea life, at least three feet thick and spanning 2/3 of a mile off to the coast, appears to be growing as microscopic algae and bacteria get trapped in it and die, the Sarasota (Fla.) Herald-Tribune reported Wednesday.
Scientists investigating whether oil from last year's Deepwater Horizon disaster was a factor in the creation of the blob say tests so far have found no sign of oil.
"It seems to be a combination of algae and bacteria," David Hollander of the University of South Florida said, describing the substance as toxic and "extraordinarily sticky."
Researchers say they are not ruling out a possible connection to the oil spill that gummed up that part of the gulf for 30 to 40 days and pumped 186 million to 227 million gallons of crude into the ocean.
"We don't know all the ramifications, the implications of a spill like this," Hollander said.