Hi all, Getting back into the hobby. I recently acquired a used 29g biocube, and was told that the (dry) sand in the bottom is "fluorescent sand from Puerto Rico", that it glows under blue light, it cannot be purchased, and he was previously offered $50 for just the sand. The seller has over 30+ years of reef experience and a very large, successful beautiful tank. My original plan was to use fresh live sand like I did in the past, but I definitely don't want to toss this stuff if it truly is something special. I cannot find anything about it online - and I thought only living things can have "bioluminescence", if that's what he meant. I did turn on a blue light and I didn't notice anything, but it was dry so I don't know if that makes a difference. Help! Does anyone here have any knowledge about this?