Every year, around the early months, Odisha’s coastline makes the news for the same reason: thousands of Olive Ridley turtles emerging from the sea, covering beaches like Rushikulya Beach and Gahirmatha Beach in one of the world’s largest mass nesting events.

For a few nights, the shore changes completely. The sand moves with life as female turtles dig nests, lay eggs, and return to the sea before dawn.

It is a spectacle India has watched for decades. 

But behind this annual arrival lies a question scientists are still trying to fully understand: How do these turtles, after spending nearly their entire lives in the open ocean and travelling thousands of kilometres, return to the very coast where they were born?

They return not to any beach, but often to the same stretch of coast where their lives began, the place where they hatched, crawled into the sea, and disappeared into open water. 

Scientists call this natal homing — one of the most remarkable memory systems in the natural world.

The beach they never forget

An Olive Ridley’s life begins in the sand.

Buried nearly one-and-a-half feet deep, around 80 to 120 eggs wait for 45 to 65 days before hatching. When the hatchlings emerge, they face their first challenge: reaching the sea.

That short crawl is an extraordinary biological act.

Researchers believe this is when the turtle begins recording the “signature” of its birth beach through a set of environmental markers.

The Earth’s magnetic field at that location, the chemical makeup of the sand and seawater, the slope of the beach, and........

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