Hello,
If you open your hood, under the battery is on a steel plate, the edge of the steel plate is protected by a rubber moulding (gasket), attached to the end of those moulding are TWO black rubber blocks, about the size you mentioned. When these blocks break off the rubber moulding the rubber moulding get loose and 'hang's down' near the engine compartment. To PREVENT this from getting caught on anything I just took it off. I took the part to my local dealer and they could NOT find it in their parts diagram. If anyone can find a part number please post it here. Thank You. Help in Hawaii.