She won't start

[Pete D]

Hello all
Electrical Problem I think....
Car won't start, (E34 Tourer 520i M50) all dash lights come on but doesn't turn over. I had recent alternator and starter replace, battery fine.
Checked under hood to amateurishly wiggle things and spotted something black and cup-shaped (distributor-looking) right in the middle of the rear of the engine bay (on firewall?!) which is hanging off! Seems to have a metal core inside and two wires coming from it. Two bolts have obviously come off the silver-edged surround. Sorry vague description, anyone know what that is?

Thanks

Update... here's a bad camera photo taken in the dark and there seem to be more than 2 bolts missing!