Water purifier. Coloured scanning electron micrograph (SEM) of coconut shell charcoal from a water purification filter. The charcoal removes odours and gases from water passed through it. The rest of the purification unit (not seen) consists of an ion-exchange resin to remove ions such as metals, chlorides and sulphates, and a ceramic housing to filter out solid material. Magnification: x1340 at 6x7cm size.