Nuggets glow

[Tautog]

I see these glowing, even in white lite, small nuggets, either lime green or bright orange. Any ideas? Sorry pic isn't better. Orange nugget, bottom left side of glass.

 

[pondman]

Maybe o sponge of some sort I have some and they glow more when blue light is on them.

 

[Tautog]

I have green ones too, and yes they do glow more under blue lites. The pic shows the nugget still glowing after being in that cup for a day. I also have sponges, but these things are hard.