Changed air filter today and found this at the front. Ruler is in centimetres.

It appears to be of the same construction material as a pipe adjoining the rear of the filter box. It smells a little like petrol. There was another smaller bit but that sort of disintegrated into millions of tiny bits when handled.

Also was lots of carbon like bits in the far right of the filter box.

TIA.

That lools like a chunk of plastic air ducting. I takie it this was on the unfiltered side of the air cleaner element? If so, then it probably wants replacing before Winter ("carburetor" icing is not funny to diagnose), but won't do any short term harm.

If it came from the filtered side of the air cleaner element, your engine is effectively running on unfiltered air, so fix it soonest.

Unfiltered side. Model is fuel injection.

The pipe it seems it came from goes from the bottom of the intake duct and leads somewhere to the bottom of the engine, although I cannot see any obvious missing chunks from pipe.

Just seen in another post that air ducting pipe (if it's same type) can be had from halfrauds for under

Sounds like the standard cold air intake then. You can replace or ignore that at your discretion.

doesn't go to teh bottom of the engine, runs to a porthole beneath the bumper where it gets almost a forced cold air induction! i think theres some kind of sensor runs to the pipe, your prolly better replacing the broken bit but it'll not be essential.