Does this look like mold or wood staining?

[Bimbop5]

Found this under my rusty fridge today when I decided it was time to clean. The floor is completely dry and one of the areas is directly under a metal rusty foot of the fridge so Im hoping its just staining or perhaps an old watermark.

That looks like mould to me.

Mould i reckon

its completely dry though. Usually it would be damp and fuzzy wouldn’t it?

It's not mould, it's staining from a drip. I have similar but not as much under the dripping tap on my oak worktop because DH didn't get round to sanding and re-oiling them in the summer when we could have the doors open, or replacing the tap.
Try bleaching to lighten it then sand.

It's water staining. Don't use a generic bleach use oxalic acid. You can get it on Amazon. It works really well on oak. Do a spot test first.

I will try that on my worktop@GodotIsntComing next spring. Thanks for the tip.

This . Oxalic acid is perfect for bleaching / restoring natural color to oak.
It can be diluted with water if the spot check comes out too light. Allow time to dry. Once treated you can neutralize the acid before any further treatment with denatured alcohol.

potential potted plant water stain.

Rusty Iron does leave black stains, as does water.
Cold metal + damp warm kitchen air =condensation.
Condensation + metal + oxygen = rust.

So my bet is that it's both - damp metal😁

Water staining from a very old leak (if it's bone dry). Wouldn't bother me.

Thanks everyone! Yep it was bone dry. Husband reminded me later that our fridge had a leak years ago that he fixed. He checked the fridge to make sure its not currently leaking and all is fine, thank goodness!

It could have been mold years ago when that happened but once dry mold can remain dormant for centuries, I was surprised to hear that. Just have to check it periodically.

It could be either mold or just rust/staining from the fridge’s metal foot. Since the floor is dry, it might be old stains, but keep an eye on it and clean it with a mold cleaner just to be safe