Wikipedia
Stool-or-mat (hieroglyph)
The Ancient Egyptian Mat hieroglyph, (originally for a stool), and later the Stool hieroglyph, Gardiner sign listed no. Q3 originally was the stool's rectangular mat; later it became the representation for the stool itself.
The Mat or Stool hieroglyph is used in the Ancient Egyptian language hieroglyphs for the alphabetic consonant letter p.