It's interesting to see the "stool" being transliterated as "p" because in Cyrillic and Greek "p" / pi is written as something that looks like a little stool: П / π! I wonder.. does that come all the way from ancient Egyptian or was it chosen to fit later?

Even if not, it serves a nice aide-memoire. A bit like how the "r" here is a mouth, and "r" in Cyrillic is Р which looks like an emoticon mouth. "s" looks like a folded cloth, ф (f) looks kinda like a snake, and Ы arguably looks like double reeds. I may be overthinking this, though ;-)