Hyphal growth?

[Chris-UK]

Hi all hopefully you can help confirm that these pictures are hyphal growth? I’m 99% sure it is looking at the pattern, but I’m no expert. 

Background info:

Dealing with a condensation issue with solid brick external walls causing black mold. I’ve been keeping on top of it, but I’m certain it was in the carpet. Took the carpet up (back to solid wood floorboards), lay these black insulation foam boards to make sure I had enough. Then stored the foam boards in the shed for a couple of weeks - it’s coldish here in the uk.

When I came back to the boards today, I found this brownish gritty patterns on the insulation boards. After some research I’m almost certain this is hyphal growth.

Do you think I’m correct and is it therefore safe to assume that the wooden floor boards have a fungal growth on them and contaminated the insulation sheets?

Thanks in advance 

[Chris-UK]

Oh, as an additional point, I bought extra foam insulation panels as I didn’t have enough, also stored these in the shed in the same place, but they are clean and have non of this growth. I assume it’s because they didn’t go into the room that I now believe is contaminated.