An egg is a hard-shelled ovoid, laid by birds for the making of more birds. It is a rare but period charge, found in the arms of Jaworsky, 1605 [Siebmacher 75]. The egg used in Society heraldry is the hen’s egg, with one end narrowing; this end is to chief by Society default. See also cartouche, roundel.
Prudence the Curious bears: Vert, an egg argent and a chief embattled Or.
Eginolf von Basel bears: Per fess gules and bendy gules and azure, in chief an egg argent.
Magdalena Flores bears: Ermine, on an egg gules a fleur-de-lys Or.