My Brightest Diamond performs at ACL Festival on Oct. 4, 2014. (ERIC WEBB/AMERICAN-STATESMAN)

When the black-and-yellow clad marching band made its first pass around the Sculpture stage, people chuckled. When they made their way into the tent, everyone dropped their jaws and what they were doing. When they came on stage and My Brightest Diamond’s Shara Worden came out to join them, the crowd buckled in for the most gorgeous, idiosyncratic set of Saturday at Austin City Limits Music Festival.

That march of the bumblebees was in service of My Brightest Diamond’s jangling single “Pressure,” from recently released LP “This Is My Hand.” Worden’s band conductor hat and massive golden epaulets were the first sign of what she soon confirmed: She is the rock ‘n’ roll Tilda Swinton. Her voice was operatic, powerful and pure; her sorcerous hand motions would have made St. Vincent proud; and her demeanor fell somewhere between alien and warm.

My Brightest Diamond fit several different shows into the space of an hour:

Old school Chuck Berry duckwalking and knee knocking mixed with Laurie Anderson performance art? “I Am Not the Bad Guy.”A moody, sorrowful dirge that culminated in a barn burning gospel howl? “Be Brave.”Western swing that made one think Ray Benson was hiding in Worden’s undercut bouffant? “High Low Middle.”A punk rock thrashfest, shredtastic chorus in between more mellow verses? “Freak Out,” which Worden said “the choreography is pretty self-evident” for. (The song brought to mind the sharp stylistic mid-song shifts of another spooky songstress: Bjork on “It’s Oh So Quiet.”)

My Brightest Diamond performs at ACL Festival on Oct. 4, 2014. (ERIC WEBB/AMERICAN-STATESMAN)

That’s not even accounting for the primal bird screams and jingle bells on other songs in the set.

As expected to anyone who’s listened to My Brightest Diamon before, the highlight was a stripped down rendition of an already stripped down song, “I Have Never Loved Someone.” Written for her young son, Worden choked up before beginning to play. She wrenched every fiercely loving emotion out of the tender lullaby with only her guitar to keep her company.

Like most treasures, this gem happened to be hidden, under the shade of the Sculpture stage tent.