Coin marks - what to do?

I am seeing spots on my coins.

Please help, advice on:
- why are they getting formed
- what should I do - should I clean them and if so with what/store in air tight containercont?

Hello, welcome to the forum!

We could use a little more information though. What were the coins stored in before? How long ago did you first notice these spots?

I'm certainly not the expert to ask, but hopefully we'll catch the attention of those who are. In the meantime I'll do my best.

For now, don't clean them.

Mona is quite right. Don't clean the coins. One thing I have learned from people here is that if in doubt... don't. I am sure you will soon get some expert advice from one of the senior members here. But as Mona said, please give as much detail as possible, perhaps even a clear close up picture of the problem could help.