Amazon's humanoid warehouse robots will eventually cost only $3 per hour to operate. That won't calm workers' fears of being replaced.

• Amazon is testing a new robot in its warehouses.
• Digit is a humanoid bipedal robot from Agility Robotics that can work alongside employees.
• Amazon says Digit is designed to "work collaboratively" with employees, not replace them.

Amazon recently began testing a new robot in its warehouse operations — meet Digit, a humanoid bipedal robot with a turquoise torso and smiley eyes.

Designed by Agility Robotics, which Amazon has invested in as part of its Industrial Innovation Fund, Digit is only the latest of a string of warehouse robots the company has introduced over the last several years. However, most of the other warehouse robots have been cart-shaped or robotic arms, not humanoid like Digit.