Some kinds of mushrooms are reactive to the UV light and will be illuminated. Not sure if there are any active varieties that are fluorescent like that, but it would be cool if there was!
It's debatable whether supplemental UVA is really all that beneficial with plants.. I have a 30-40w LED bar but never tried using it to grow with. I go straight for UVB bulbs if anything, which is even more highly discouraged against in the mycology realm. I just use it for artwork
I say try it over a tub though!