Because we are drawn to the bright and the white, many of the commodities of our daily lives are manufactured to artificially express these properties, and in particular, to make them look cleaner or newer than they actually are. As a consequence of this, much of what we make contains synthetic compounds called optical brighteners. These chemical agents work by fluorescing, that is by absorbing natural (from the sun) or artificial (from standard lighting) ultraviolet light and converting it into other colours of visible blue light, to make objects appear whiter and brighter than they otherwise are. Optical brighteners are thus commonly found in our clothes, washing powders, and importantly here, paper. In these images the slime mould Physarum polycephalum has grown on paper and is observed under normal daylight and also under ultraviolet illumination. Under UV, the paper fluoresces a blue colour because of the optical brighteners in it, whilst the slime mould appears black. This is because it absorbs UV light. This might be a manifestation of a protective mechanism whereby it produces UV absorbing pigments which protects the organism against the damaging effects of sunlight. Such a pigment my offer a natural protective factor for suncream.