Alessandra Ambrosio, Fergie -- Nice T, Great A at Coachella (PHOTOS)

Coachella hotness is not just for kids ... check out exhibits A and B.

EXHIBIT A: Alessandra Ambrosio brought the girls to the concert Saturday and left her kids at home. She's 34, and lookin' mighty fine.

EXHIBIT B: Fergie showed off a nice piece of lace as she had fun in the sun. Again, 40 looks amazing.