ᐅ Strange stains on hardwood flooring – what causes them?

Hello,
I have noticed some strange stains on the parquet floor under my dining table. See the picture below.
I tried wiping the stains with water, but nothing comes off.

Does anyone know what this is? It looks really strange.

Star_trek300 schrieb:

Does anyone know what this is?

It looks like grease stains.

Is there anything that can be done about this, or does it need to be completely removed?

They sometimes disappear on their own.

And if not, what can be done?

They fade over time, and oiling the entire floor also makes them less noticeable.