[SOLVED] What is this part good for?

[MdAyq0l]

Recently I discovered the following plastics part during cleaning the floor near my Dell Vostro 3750:

It could have fallen out of the notebook or some other device (a steriliser box, an SSD, an SSD external casing, a sewing machine). The size is about 19 mm × 9 mm × 3 mm. Does anyone have any idea where this part might come from and what its purpose is?

 

[Alabalcho]

Looks like a (dust) cover for some of the ports - HDMI, network, SD, although none of these usually have taps.