Scientists have wondered for decades how female sea turtles can cross thousands of miles of open ocean and still find their way back to the same beach to lay eggs, and researchers think they may finally have an answer: magnetics.

The sea turtle’s ability has been baffling because the open ocean where the sea turtle spends its time is vast and without features, but the turtle still finds a way to get back to the same location every two or three years — called “natal homing.”

Scientists have long thought that the Earth’s geomagnetic field may help explain the phenomenon, but now there is some hard evidence ot support it, according to a Los Angeles Times report.

Researchers published a paper in Current Biology this week that shows that small changes in the Earth’s magnetic field will affect where a loggerhead sea turtle buries its eggs on the coast of Florida, which suggests the hypothesis is correct.

The magnetic field around Earth is strongest at the poles and weakest at the equator, and intersects the Earth at different angles called “inclincation angles.” It appears that turtles have evolved in such a way to use these inclination angles as an internal GPS, according to the paper, which was put together by a team from the University of North Carolina.

The researchers studies 19 years of data from the Florida Fish and Wildlife Conservation Commission on sea turtle nesting sites on the Atlantic Coast of the state.

Since the Earth’s magnetic field is constantly changing, researchers hypothesized that when magnetic signatures of neighboring beaches were closer together, there would be more nest on that stretch of beach, and they found that that was indeed the case: there was an avrerage increase of 35 percent in nesting density in places where the magnetic signatures converged, whereas it decreased by 6 percen twhen the signatures diverged.

There is more work to be done, as scientists don’t know how the sea turtle detects the geomagnetic field, although they suspect it may have tiny magnetic particles in their brains or inside their bodies that act as a compass. However, there is not yet any hard evidence for this theory.