Though researchers have some best guesses, nobody seems to know for sure why exactly a killer whale in Washington state was wearing a dead fish as a hat.

A resident orca off the coast of Washington state was recently spotted sporting a dead salmon on its head. The phenomenon was first documented in 1987, when whales from three separate pods were seen wearing salmon like hats.

An especially popular killer whale put a dead fish on his head, in a throwback to a fashion last seen in the 1980s.