Sharks know a thing or two about fins — their direct biological ancestors practically invented them — and if there’s one surefire way to piss off the ocean’s most feared predators it’s to paddle out with a nonsensical fin set-up.

Today in Australia a man surfing at Lennox Head was thrown off his board by a shark, which proceeded to attack his five-fin setup, leaving bite marks on the stringer and forcibly removing one of the offending articles. Yesterday a bodyboarder was left seriously injured by a (fin-related?) attack at Ballina, just around the corner. The shark that bit his legs is believed to have been a great white shark.

Last year a surfer riding a five-finned board was attacked by a great white in California; the man was injured, but thankfully it was the board that incurred the brunt of the shark’s wrath.

Fortunately in this case the surfer escaped unscathed, but in future he will surely think twice before entering the water with a similar fin arrangement. The 2015 Oz Grom Open was supposed to get underway at Lennox today, but has been postponed in the wake of recent events. Apparently the surf there was pumping, and there wasn’t a soul in the water — an unusual occurrence at Lennox to say the least.

Robin Mather, a witness on the scene, told ABC News: “We went down and there was a bunch of surfers around him, and I just looked at the bottom of his board and one of his fins was missing. There was puncture wounds, so like bite marks, all the way through the back of his board and he looked really shaken up. It was really, kind of heavy and he was fine, just looked super rattled.”

“A guy from the bank whistled at me and just gave me the fin signal with his hand, so I worked out what was going on,” surfer Buzz Tilley told ABC News. “I sort of wanted to keep surfing but then I realised I was going to be the only one out there in another 30 seconds.”