I suspect it's a smoke detector. Is that a light in the center?

I'd look for something leaking in the bathroom. It may or may not be close to that device.

Maybe a sprinkler system if that isn't a light in the center.

No light in center, water is pouring down from it. Not sprinkler either., thanks for replying, Greg2015 and Randy427.

So what is that in the center? Just a hunk of metal?
A well lit, in-focus picture might help. And maybe something that shows the size of it. I'm picturing something that's only a couple of inches in diameter but I suppose it could be the size of a dinner plate.

I can't be sure without a better picture. It almost looks like an old passive infrared sensor. But many things have that same general shape as it has been deemed an expected intrusion in homes. So ir sensors, glassbreak detectors, smoke alarms, etc., all are made in that shape.

Thank you all for your replies, i was told it is the sound device for the alarm system, as to the water pouring down from it, I had a leak in the attic, that found its way, through the alarm sensor.