While putting up radiant barrier I came across one spot in my attic where I saw some round black sand particles on the floor and noticed that it was on some of the insulation - upon puling the insulation away I see spotting on the wood and more particles.

I don't think it's mold because of the sand particles - it would appear that the spots on the wood were wet at some point leading to the discoloration around the material. Thought maybe it was termite frass but very odd to only be in this one area and no signs of terminates on the wood. Rodent or bat crap maybe or could it just be roofing mterial from the shingles that fell off when they did construction years ago?

Here are some pictures, anyone know what this is? The particles stick out from the drywall board and so far I only see them behind one of the insulation batts and very localized to this area.