[Beryana]

AOII doesn't officially have a mascot either - the panda is unofficial and I know a few chapters that use something else.

That is all part of what makes each group unique. There is no cookie-cutter form to creating a sorority/fraternity. This is a rhetorical question, but Delta Zeta probably has some meaning which is similar to a motto without actually saying "this is our motto. . . . " And, as far as an open motto, a LOT of groups don't have those. They have marketing taglines but not open mottos like Gamma Phi Beta and Kappa Delta.