u/Furgling

We removed 40 year old linoleum and each square was pretty much outlined in a dark line just from dirt getting in. However, under the fridge and stove there was more dark spots. I don't know if it's the heat through the linoleum making the dark patches or if it's mold.

I know there are mold kits at Lowe's but I read those are inaccurate as they can just catch mold spores in the air.