It's a bit off topic, but let's see...
I live in a condo, and the devices pictured below are found everywhere: in flats, in corridors, even in the car park (they are attached to ceilings) and I have no clue what they are. Would anyone know ?
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It is in fact a Wi-Fi Extender.
I'm guessing it is a different looking version of this: WiFi antenna
I would say that it is a covered sprinkler (fire extinguisher). It will react to temperature rise and start spraying water. The water jet will pop off the cover, which protects the sprinkler until it is needed.