Hi!
Today I examined the roots of my new plants. After looking at my Echinopsis subdenudata, I found a black spot where an areole should be, and the yellow, kind of baggy base of the cactus. This yellow part is not as firm as the rest of the cactus, but not mush, either. I have put a picture below.
Is this a sign of rot? Or is it just an areole below the dirt line?