Between 2007 and 2019, human feet began mysteriously washing up on the coast of the Salish Sea in Canada and the U.S. A total of over 21 individual feet, still in their shoes, were found on various beaches in the area.

The first two feet discovered were both right feet and size 12, found within a week of each other. As time went on, more feet continued to appear, almost always still in their shoes. This sparked rumors of a serial killer in the area, as people tried to make sense of why these feet were showing up.

The real explanation is more straightforward, though. When a body sinks to the sea’s bottom, scavengers quickly target the soft parts of the body, which are easier to consume than bones. Our ankles are composed mainly of ligaments and soft tissue. Once scavengers eat away this tissue, the foot can easily detach from the body.

So, why didn’t we see feet washing up before 2007? It comes down to modern sneaker design. Sneakers in the past 20 years or so are made with light foam and air pockets in the soles. This design allows the sneaker to act like a balloon once the foot detaches, bringing it to the surface.

Thanks to the buoyancy of these sneakers, over 15 missing person cases have been solved. This constant mystery had baffled many, but sometimes the simplest explanations are the truest.