Especially when it's a silvery wingless insect. Lepisma saccharina, commonly known as silverfish after the way their bodies glisten a silvery colour in the right lighting and the way they wriggle like a fish when moving.
I found this dead one .....
Body length 10mm
.... and put it under the microscope.
The body is covered in tiny scales which reflect the light:
They are very fast movers on the flat. Too fast for most predators and as they like to stay in dark, damp places they are often too fast to be spotted by us.