Many people are learning the surprising truth about their kitchen appliances—the actual function of the microwave ring cover—in a recent revelation that has gone viral on the internet. This seemingly unimportant part has been hiding in plain sight, and most people are unaware of its purpose.

Frequently misunderstood as a straightforward protective covering or a component of the microwave’s design, the ring cover is actually essential to the device’s functionality. It contains the roller guide and turntable support ring, which make it easier to rotate the glass tray and guarantee uniform food cooking. Microwaves wouldn’t heat food evenly without this part, which could result in cold spots and uneven heating.

Users have responded to this new knowledge with a mixture of surprise and laughter, with many posting about their surprise on social media. It demonstrates how commonplace objects can conceal mysteries that even people who use them on a daily basis are unaware of.

As this information spreads, people are becoming more aware of the engineering that goes into everyday appliances and paying more attention to how they are made and how they work.