Yes, I'm sufficiently freaked-out. My question is: Where is this piece going to be and how do I get to it?
If there is any clearance between the flywheel and the bell housing it is probably in the lowest part or bottom. The magnet or compressed air is worth a try. Next step might be to separate the engine from the transmission, move it forward if possible and see if the piece falls out or is visible? Or, easier yet, if possible, slide the transmission back a little from the engine. If you can hear it it is being picked up by the flywheel and bounced around inside. Maybe it will eventually wear itself down to a smaller size and not be picked up any more? Probably not, better to bite the bullet and get it out. Let us know how it works out. Good luck with the magnet, it might just work. I have had good success with one retrieving lost nuts and small tools that have dropped out of sight and not hit the floor.