99 Boxster Metal in Combustion Chamber

[Alita]

I have a 99 Boxster that I quit driving after it was accidentally over filled with oil. The oil was changed, spark plugs and filters changed. No metal was found. Car ran but drove roughly. Previous to this the O2 sensors were bad. Crank shaft sensor was changed. Battery was replaced. I hired a mechanic to look the car over and replace the sensors and probably the cats. He opened the engine compartment, using a telescoping magnet he started extracting bits of broken metal pieces from inside the intake of the combustion chamber.

Can anyone tell me what this may be?
He's wanting to remove the engine and I wonder if that's necessary??
I've done research on IMS bearing problem. Is this related?