Memory foam pillows?
I just bought a memory foam pillow, and it is the first time I have ever used one. Am I supposed to buy a cover for this? I didn’t think so at first, but now it is getting pretty dirty pretty quickly.
OK thank you. Are there seperate sizes specially for memory foam? Or should I just buy standard?

yes buy a cover. any standard case or queen on should work.
Yes, you should definitely cover it. I have many memory foams and all have pillow covers.
yes, memory foam pillows need covers just like any other pillow. buy a standard size.