I pulled the item in the photos from near the front left wheel, inside the wheels, as it was hanging down from the undercarriage of my S Type.
Notice it has 2 holes, it appears to have been mounted to the car. The outside feels like a trash bag, the inside is a grey foam.
It is important? Did it even come with the car??
Thanks.

 

I think that used to be part of the undertray. They were kind of half-assed secured onto the undertray. I figured they were there to soak up any oil drips. Usually they just get old and brittle and you find them in odd places.