strange glow

[libmo]

I was looking at my tank early this morning with only a dim flashlight. Right after I went by a small hole in a rock, for about a second or two the hole glowed bright green. It was very similar to a lightning bug, but not quite as bright. I know it was very early in the morning but I am sure that is what happened. What could possibly be in the rock to cause that to happen?

 

[Slatts]

I saw the same thing the other night only not in a hole but close to the sand bed. It looked like my pep shrimp was eating it cause it was right by his head. I thought I was just staring too long. It was neon greenish.