What is this?

>>927820
Vinegar should kill it, but you'd need to wait for it to essentially die and crumble out of the fibers (assuming they have not been permanently marred by the mold) before the discolouration goes away. I'd try hitting it with vinegar, letting it sit for an hour or so, then a few days out in the sun followed by a wash.

Or, ya know, a new pillowcase from goodwill for 20c..

>>927822
I like my case because it's custom-made, and it pays double because of the stitching.
I'll try anything as long as these bastards are gone. I can try hydrogen peroxide mixed with hot saltwater and chlorine and go for the overkill.
How long will I leave on the basin for it to disappear instead of an hour, overnight?

>>927823
Yeah, if you can. I was going to suggest an overnight soak but didn't know how much [chemical] you had on hand, but if you're keen to and have enough to soak it completely, give it a shot.

>>927831
Thanks for the advice!

>>927832
I'm just waiting for the chemicals to work. Just now they wouldn't get off.

Personally, I would trash the pillow. Surface mold means there's probably plenty of spores inside the pillow fibers as well. Don't like the idea of my face being near that. A thorough soak in vinegar and peroxide should kill it but may ruin the texture of the pillow.