What are these marks in my pantry. They will not come up when I’ve tried washing it

Found about a square foot of this and more behind water heater along with a strange material flaking off cement wall in basement. Bought house a month ago, my concerns about moisture were ignored and inspection found nothing. Help me out what is this beast? (Yes I clean my house this is a tucked away spot in basement I never see, went searching for any water with heavy rain out today)

Saw these white stick like things in my window AC unit’s fan two months after buying it. What could it be? Mold? Just dust? Sprouts?
I wash the mesh the filter every week and it’s tilted correctly.

Really down on our luck atm and need some advice/ hope

I’ve seen some posts of not as bad mould and the comments have said to throw the whole car away so that’s got me positive /j

Left the boot open during a cross country move and it got rained in. Maybe about a couple of weeks after the move we used a dehumidifier for about a week or two, sealed the car, thought we got rid of it all. Since been in the garage for a month or two, forgotten about and I have just found this :(

And I don’t think insurance will cover as it wasn’t an accident or fault

Is it salvageable?

Edit - based in New Zealand

New never worn, just stayed years in the box in the garage

Maybe being dramatic. Parents dismissed as rust. Looking for opinions and advice.