Puzzled

Hi, could someone please let me know what Molded sponge rubber is called and it’s part number,  when you take off the engine cover it seems to go around the top of the rocker box cover , it also seems to be secured at the back of the rocker box cover by two clips, is it something to do with being an anti vibration strip when the engine cover is in place ?? , also the cost to renew it, thank you.