Can roof tiles be stored outdoors..?

[A bygg]

Ok. The question sounds a bit silly like "can the roof be outside?" 😁
I have bought some used roof tiles. They are clay, not concrete tiles... I believe they are from the 70s. I want them to repair/supplement my roof.
Right now, they are outside. Stacked on a pallet.
Of course, it's raining on them...

Can the tiles withstand being like this?
Is there a risk of damage, ice cracking them?
Checked today, there's a small amount of something white growing, like light-mold.

No, I don't have a sensible place indoors.
I can, of course, put a sheet over them to keep them from getting wet....

 

[Markarbetaren]

No, it's not working at all! Go to the nearest department store and buy tarps, you also need to cover the roof of the house😁

 

[Rickard.]

A tarp won't do, it needs to be at least +16°C....

No, but seriously, a pallet at the bottom is good, and I think you can throw something over it to keep most of the water away. However, I would restack them standing as they come when you buy them. I don't like the idea of the bottom tile having ≈100kg on it, another advantage is that snow and water that blows in just runs off. Brick may be a good roofing material, but standing water and winter are not so good for it.