Marian Robinson, mother of former First Lady Michelle Obama, has died at age 86, the family announced Friday. She passed away peacefully in the morning, according to a statement.

Michelle Obama shared a heartfelt tribute on social media, calling her mother “my rock.” She wrote: “She was there for whatever I needed—the same steady support for our whole family. We’re heartbroken to lose her today.”

Former President Barack Obama also honored his mother-in-law online, calling her one-of-a-kind. “We feel lucky to have had her in our lives,” he posted. “We’ll spend our years trying to live by her example.”

Born Marian Shields in 1937, she married Fraser Robinson III, a Chicago water department worker and WWII veteran. The couple raised Michelle and her brother Craig in a modest South Side home.