What do you think these mystery marks could be?
These are pictures of my friend's bedroom carpet. She said these roundish stains have appeared quite mysteriously, and they have her baffled. I have to admit, they are the strangest stains I've ever come across. I haven't seen them in person (may do so this week) but based on her description she said they're more 'discolorations' than anything else. Any insight would be appreciated!