When Helen Pheasey encounters poachers on Costa Rican beaches at night, she no longer tries to shoo them away. Instead, she actually hopes they’ll take eggs from a sea turtle nest she’s been monitoring. That’s because those nests contain a GPS tracking device disguised as an egg, and getting poachers to take them is key in her quest to understand the black market for turtle eggs, a favorite bar snack here in Costa Rica.

The GPS-enabled fake turtle eggs are the brainchild of Kim Williams-Guillén, an ecologist for the NGO Paso Pacifico, who lives on her own pig farm in Detroit.

In 2016, she entered a competition put together by the U.S. government that aimed to foster tech-based ideas that could expose, and stop, the illegal trade in animal parts. Hers was one of the winning ideas. Now, Williams-Guillén collaborates with Pheasey, who's testing the decoy eggs in Costa Rica.

Some of the eggs found in bars are part of Costa Rica’s heavily regulated, small legal trade, but many are sourced and sold illegally by poachers.

“You basically do a shot; they will usually do it with alcohol, but the egg itself is in a tomato salsa and chili,” says Pheasey, a conservation biologist at the University of Kent, in the UK.

Because almost all sea turtle species are endangered, that’s a practice that Pheasey and other conservationists would like to see end.

The decoy egg project is the first of its kind, Pheasey says, so she’s still figuring out how best to prepare and plant the 3D-printed eggs.

Right now, the routine goes like something like this: Every night, Pheasey places a SIM card inside each one, and charges them, so they don’t run out of battery power too soon after they’ve been taken from the nest. Then, she seals the eggs, and paints the opening so they look like the real thing. When it’s sufficiently dark out, she heads to the beach and waits for a nesting female to show up. Pheasey drops a fake egg inside the nest after the turtle has laid about half of her eggs around 45 in the case of the olive ridley sea turtles she’s been working with most recently — because that’s low enough in the nest to prevent predators from getting at it and high enough that poachers won’t leave it behind if they find the nest.

Eventually, Pheasey hopes to use the decoy eggs to study the black market in Costa Rica and other parts of Central America, but for now the goal of the study is simply to make sure the eggs work. Still, Pheasey has been keeping an eye on the eggs that do get poached. On one occasion, a decoy egg traveled 155 kilometers from the nest it was planted in.

“It's really exciting because this is legitimately working,” she says. “We've got an egg leave the beach and go to a place that's like the handover point. And then the next day, I can pinpoint the exact house that it's in.”

Pheasey realizes that the decoy eggs raise ethical questions; after all, she’s running a trial where participants have no idea they’re participating — or being tracked. But Pheasey is confident that the work is harmless.

“With covert research, it’s acceptable if it's the only way you can collect that type of data,” she explains, adding that her study won’t be used to get anyone arrested. That said, she does hope the GPS eggs will be used by police one day. “This is a law enforcement tool of the future,” she says.

VICE News went to Costa Rica to find out why these fake turtle eggs are necessary — and to document the planting of a fake egg in a turtle nest.