I had to assemble in front of the left and right speakers of my bed. Since the built-cable not quite enough, it wanted to extend to one side of the pit. After I opened the speaker a lot to me immediately the missing voice coil including magnet. There was no cable to the speaker. Where else could they cope? To control I immediately even opened the second speaker - also here the exact same thing.
EDIT: I have found that it is a passive radiator. Here you can read a bit about it: [...]
