An orb is a ball, banded and with a cross atop it; also called a “mound”, it is a symbol of the world (and thus, when used as regalia, of temporal sovereignty). As an heraldic charge, it’s found in the arms of Friellas c.1540 [Nobreza xxxiiº].
In Society heraldry, the term “orb” was once used to refer to a featureless ball, synonymous with a roundel. This usage is no longer followed; orbs and roundels are considered distinct charges, with difference granted. For related charges, see sphere.
Fionn mac Con Dhuibh bears: Azure, three orbs argent.
Randolph Wedderlie bears: Or, an orb gules.
Margrett Schwarzenberger bears: Per chevron argent and sable, three orbs counterchanged.