Might have been an old wasp nest covered in black carbon.
Yes, they still make mufflers for them, lol. You can get one from Cub Cadet, or an aftermarket company like Stens and Prime Line. Look up the part number and look on ebay. Don't buy a super cheap one, they are tin can thin and not quiet at all. But you don't have to get the like $60 one from Cub Cadet that is, unless you want to, they are very good. Middle of the road price. Stens seem to be OK. Nelson are also good and may have been who made them originally.
