Is this arthropod non-intrusive and recommended to be left alive?

Question

I am in Portugal (Lisbon) at the moment, and when leaving my room late at night (12 pm ~ 04 am) I usually face about 4 of these arthropods in the corridors:

(For reference, the "line" in the image is a standard separation on the floor. This particular example of the animal is a little smaller than a nail.) They seem to have quite variable sizes and walk primarily on ground. Also, as implicit above, they seem to be active primarily during the late night. (I don't see them much often, if at all, during the morning/afternoon.) They can be quite fast, but if left unharmed do not move much. They also appear to take shelter inside the walls.

From what I searched, it seems possible that they are centipedes. I've seen sites saying that they are useful to keep other less pleasant animals at bay. My questions are: What are those animals, and should I leave them be or not?

Answer 1

This appears to be a silverfish, a very common household "pest" in the Lepismatidae family of insects.

^{Photo Credit: Dong-Hwan Choe. Source: UC IPM}

Silverfish are silver/grey and (like all members of the Zygentoma order) have three distinct, tail-like caudal appendages from their posterior end -- really, two large cerci with a central long filament. [Sources: 1, 2, 3].

According to Wikipedia, you can find them all arround the world:

Silverfish are a cosmopolitan species, found in Africa, the Americas, Australia, Eurasia, and other parts of the Pacific.[8] They inhabit moist areas, requiring a relative humidity between 75% and 95%.[9] In urban areas, they can be found in attics, basements, bathtubs, sinks, kitchens, old books, classrooms, and showers.[3]

They are relatively harmless due to their weak jaws [source], and their presence is typically a larger nuisance than the damage or disruption that they cause.

We have a number of posts already identifying silverfish and asking about management advice. Try yping "silverfish" into the Search bar at the top of the page to search for more information.