The white things with holes are ceramic rings and are one of the best types of media to have as they provide good surfaces for the bacteria and help randomize the water flow, reducing the possibility of tunneling (water missing out on being filtered.) The carbon is not needed and the space it uses can be better used my more ceramic rings, pebbles or sponge material. Sponges, which normally will be provided in a couple of different types are good and important.
There are sometimes various "ammo-chips" or other type of white stuff provided to chemically reduce ammonia I believe (members help me out here?) and these types of media are definately -not- needed and again, should be replaced so that the space is better used for good biomedia.
~~waterdrop~~