Can you please identify these yellow dot parasites which grow on non-living surface?
This looks like the work of an insect, perhaps a fly.
You can check by experimentation.
Try covering part of one surface with a fly-proof covering.
Take photos at weekly intervals of exactly the same area, compare images.
black-and-white images below from
Forensic Science International 137 (2003) 152–159
&quot;Distinction of bloodstain patterns from fly artifacts&quot;
Mark Beneckea, Larry Barksdale
DOI: 10.1016/j.forsciint.2003.07.012
Bar on images is 1cm