A dangerous jellyfish appeared near the Jersey Shore ahead of the Independence Day weekend, but scientists believe it may have been coincidental.

According to Live Science, a dead Portuguese man-o-war washed ashore on Sunday, June 21 on Long Beach Island. Normally native to much warmer waters near Australia or Mexico, one scientist thought the jellyfish was pulled over to New Jersey by a particularly strong gulf stream.

"It probably came up with the Gulf Stream and then we had a little bit of a north swell move in. So that [critter] might have drifted in," John Tiedemann, director of the Marine and Environmental Biology Policy Program at Monmouth University, told Live Science.

But Ann Delaney, a resident of Stone Harbor and regular beachgoer, told NJ.com she noticed one washed ashore after the first reported sighting. She noticed its blue and purple color and thought it was a plastic bag.

"I walk (the beach) every morning and I usually pick up plastic, and I thought it was a colorful Ziplock bag," Delaney said. "I remember reading a post about the man-of-war found on Long Beach Island... I realized that it could be that. So I didn't touch it. I touched it with my shoe but I didn't pick it up."

The Harvey Cedars Beach Patrol posted a public notice on their Facebook page to alert beachgoers of the danger these Portuguese men-o-war pose. They have tentacles as long as 30 feet and have been known to sting humans, causing extreme pain, paralysis and even potentially deadly chemicals.

Paul Bologna, associate professor of biology and molecular biology at Montclair State University, told Live Science the men-o-war jellyfish can even sting when they appear to be dead.

"The stinging cells are like a little trap - like a mouse trap - and they're waiting for some stimulus to irritate them, and then they'll explode," he said. "Even when [the man-of-war is] washed up on the beach, those stinging cells are still active, and they have the potential to sting you."