bmwfive

I have found some wires in the boot of my car that clearly look like they are part of a retrofit or mod.(they are separate from the OEM looms and are taped to the car)
I have traced the wires back to behind the fuse board above the battery.

The wires lead to a black module which has just been glued to the car. Does anyone know what this could be - a tracker perhaps?
There is a grey wire which looks as though it might be an aerial/antenna. There is also another two wires which are obviously positive and negative.