Top left: hieroglyph Aa1 (stylized); right: in color, 12th Dynasty. Bottom left: hieratic, 5th Dynasty; right: 19th D. (similar forms common 11th-20th).
Disputed; a sieve and a human placenta have been proposed as possibilities. In the Archaic Period it was generally crosshatched horizontally and vertically, and this form sometimes appeared through the Old Kingdom. For most of Egyptian history through the New Kingdom a form with only horizontal striations was used. A form with diagonal striations instead was rare before the Libyan Period. This glyph was conventionally colored green. In some representations that lack striations, only its color differentiates it from other circular glyphs.
Gardiner, Alan (1957) Egyptian Grammar: Being an Introduction to the Study of Hieroglyphs, third edition, Oxford: Griffith Institute, →ISBN, page 539
Henry George Fischer (1988) Ancient Egyptian Calligraphy: A Beginner’s Guide to Writing Hieroglyphs, New York: Metropolitan Museum of Art, →ISBN, page 12
Peust, Carsten (1999) Egyptian Phonology: An Introduction to the Phonology of a Dead Language[1], Göttingen: Peust und Gutschmidt Verlag GbR, page 48
