A troop of monkeys has been caught on camera mourning one of their dead, without realising the 'corpse' was actually a robot.
BBC's new nature show Spy in the Wild uses lifelike robots to get closer to animals in their natural environment than any human camera operator can.
"We were never quite certain what we were going to discover," executive producer John Downer told UK media.
They were shocked to see a male chimp adopt an animatronic kitten, but truly blown away when a group of langur monkeys in India accidentally "killed" the baby they'd come to know and love.
An adult monkey perched high on a branch drops the robot, and another rushes over to see if it's okay. They quickly realise the robot - which isn't moving - is 'dead'.
"The monkeys gather around the motionless spy creature as if it is a real baby," says the show's host, former Doctor Who star David Tennant, in a preview clip uploaded to YouTube.
Monkeys take turns at checking the 'corpse', and a calm soon descends on the tribe.
"They act just as they do when their own babies die," says Tennant.
The monkeys start hugging one another, with parents clinging tight to their young ones.
Spy in the Wild debuts on BBC1 on Thursday night. The series, shot in 4k quality in 21 different countries, took three years to put together.
The animatronic animals are so realistic they fooled more than just a group of monkeys.
In one episode, a male tortoise attempts to mate with its robotic likeness.