What are these things that look kind of like sprinklers in my ceiling?
Shape, location, and wiring but not pipe strongly suggest that they are heat detectors - part of a fire alarm system (whether or not that's an active alarm system, you get to find out somehow.)
Modern ones tend to be &quot;sleeker&quot; and combined with smoke detectors, but this is a fairly common form for older ones.
They are useful for locations that have nuisance smoke but real fire potential, and also I'd guess were commonly available earlier than smoke detectors were.