m0useanswered grow question 9d ago Does not look like WPM to me. but I could be wrong.
It does have dried mineral vibes to it. or almost like a silk/web.
WPM should get fluffy and suff not be smooth and tint like.
Pluck to be on the same side and monitor the plant. look aorund where it was found for things that might have dripped on it and dried or it brush up against like a bleach rag or peroxide.