Fabric washing products contain Fluorescent Whitening Agents (for a "brilliant white"). Any white/light clothing washed in these products will glow under UV light.
The mineral fluorite, (which is actually a common substance around 'Pod Towers), will 'glow' under UV light, as do many other minerals (which arealso common round this household). It is from this mineral that the word 'fluorescence' (meaning to luminesce under UV light) comes from.