Orcas off the coast of Washington State are balancing dead fish on their heads like it's the 1980s, but researchers still aren't sure why they do it.

Sometimes, nature surprises us with behavior that feels more like a quirky human trend than an animal instinct. That’s exactly what’s happening off the Pacific Northwest coast, where orcas are once again donning “hats” made from dead salmon.

West Coast killer whales were last spotted sporting expired salmon in the 1980s, according to Live Science. After a nearly 40-year hiatus, whale watchers and scientists witnessed the resurrected fad last month off Point No Point in Kitsap County and in South Puget Sound.

In the cold waters of Puget Sound, Washington, a peculiar fashion statement has resurfaced after nearly four decades. Orcas, the ocean’s charismatic black-and-white predators, are donning “salmon hats” again—balancing dead fish on their heads as they swim.