paul,

the spoungy things you found are cork gaskets that seal the push rod cover around the spark plugs. they are essential if you want to avoid massive amounts of oil coming out and around a spark plug.

when you purchase a new push rod gasket set, the little round corks rings are included in the set. also note that when you pick up the box for the side cover gasket set it will most likely look too small to match the dimensions of the actual cover. this is because they package the perimeter gasket folded over with a couple of carboard tubes to prevent damage to the cork. takes a little work to get it flattened out before you install it but i my guess is they are trying to cut down on the amount of packaging required to ship.